A friendship fractures beneath the Crimson Moon as Bygone Days exposes one of Khaenri’ah’s oldest wounds

Some of Genshin Impact’s most important tragedies happened long before the Traveler ever set foot in Teyvat. HoYoverse’s new Story Teaser: Bygone Days turns its attention back toward one of them, using the Mirror of Remembrance to revisit the relationship between two scholars whose choices would eventually place them on radically different sides of history.

Released on October 7, the animated sequence expands on events from Version 7.1: A Rekviem for the Underworld, returning to ancient Khaenri’ah and the youth of Eftirvit and Hroptatyr. What initially appears to be a story about two brilliant friends and their ageing professor gradually becomes something considerably more important: an early confrontation with the power of the Crimson Moon, an attempt to interfere with death itself and the moment a friendship breaks over knowledge one of them refuses to share.

For players following Genshin Impact’s increasingly central Khaenri’ahn mythology, the significance is obvious. Hroptatyr will eventually become “The Wise,” one of the Five Sinners of Khaenri’ah, while Eftirvit’s path leads toward the man later known as Pierro, The Jester, and the organisation that will become the Fatui.

The tragedy shown in Bygone Days takes place before either man becomes the figure players know in the present.

The Mirror of Remembrance looks beyond ordinary memory

HoYoverse introduces the teaser with a deliberately cryptic description.

Through the Mirror of Remembrance, the viewer witnesses “a memory of a friend” and “the past of a sinner,” while being shown how a blessing and a curse can originate from the same essence before inevitably diverging.

That choice of wording is particularly important after Version 7.1.

The Mirror of Remembrance appears during the current Snezhnaya Archon Quest and functions as a way of accessing preserved events from the distant past. Rather than presenting Khaenri’ah exclusively through Dainsleif’s recollections, ancient books or fragmented accounts, HoYoverse can now directly dramatise relationships between people who lived before the Cataclysm.

Bygone Days uses that opportunity for something notably intimate.

There are no armies marching through Khaenri’ah, no colossal machines destroying cities and no immediate depiction of the Cataclysm itself. The teaser instead focuses on conversations beneath a flowering tree, research conducted inside the Universitas Magistrorum and two friends trying to save someone important to both of them.

That smaller scale makes what follows considerably more personal.

Eftirvit and Hroptatyr were once simply two scholars

Long before becoming one of Khaenri’ah’s Five Sinners, Hroptatyr was a scholar of extraordinary talent within the Universitas Magistrorum, the institution that would eventually place him at the centre of the kingdom’s intellectual establishment.

Eftirvit studied alongside him.

The two discuss ambitious ideas that already reveal the kind of civilisation Khaenri’ah had become. Their conversations concern subjects such as celestial phenomena, Azosite, the manipulation of physical laws and whether powers associated with the heavens could be understood, summoned or reproduced through research.

These are not people living in a conventional medieval kingdom. Even before the disaster that destroys Khaenri’ah, its scholars are attempting to understand forces lying far beyond ordinary human knowledge.

Hroptatyr and Eftirvit approach that pursuit differently, but the teaser makes clear that there was once genuine familiarity between them.

Their professor, Mimameith, even sees the two together during this earlier period of their lives. She is already elderly and physically deteriorating, but remains closely connected to both students and openly hopes that she will live long enough to see what they eventually accomplish.

That wish becomes the emotional centre of the entire memory.

Professor Mimameith’s condition turns knowledge into desperation

Mimameith is not simply dying of old age.

The Version 7.1 flashback establishes that her declining condition is connected to previous work involving Abyssal research carried out for Khaenri’ah’s leadership. Whatever exposure or damage she suffered cannot be reversed through ordinary means.

For Eftirvit and Hroptatyr, the problem therefore becomes both personal and intellectual.

Their teacher is dying because of a field of research that pushed beyond safe human limits. The obvious response would be to accept that some consequences cannot be undone.

Hroptatyr does the opposite.

He searches for another extraordinary power that might solve the problem.

His answer lies with the Crimson Moon.

The Crimson Moon offers a way to cheat death

Hroptatyr eventually arrives with a research grimoire containing a possible method for extending Mimameith’s life.

The process is connected to the power of the Crimson Moon, an enormously significant concept within Khaenri’ahn history. Before the Eclipse Dynasty ruled the kingdom, the Crimson Moon Dynasty represented an earlier era whose symbols, beliefs and powers continue to echo through the game’s present-day lore.

Hroptatyr believes that something hidden within that power may allow them to prevent their professor’s death.

The teaser shows the experiment directly.

An open book becomes the focus of a ritual as violet energy gathers above its pages. A complex circular diagram forms in the air, surrounded by supernatural energy as Hroptatyr attempts to make the theory work.

For a moment, it appears that the two scholars may genuinely have discovered something capable of changing the rules governing human life.

Then it fails.

The magical structure collapses.

Hroptatyr immediately concludes that the underlying theory is wrong.

And that should have been the end of it.

Eftirvit does not believe him.

The failure matters less than what Hroptatyr refuses to explain

The most consequential part of the sequence is not the failed ritual itself.

It is Hroptatyr’s reaction.

Rather than continuing the research or explaining precisely what the experiment revealed, he decides to abandon the entire approach. Eftirvit challenges him, convinced that his friend has discovered something he is deliberately withholding.

Hroptatyr refuses to provide the answer Eftirvit wants.

That silence becomes the fracture at the heart of Bygone Days.

The game does not frame Eftirvit as somebody furious merely because an experiment failed. He is angry because Hroptatyr appears to understand why they should stop — and because whatever Hroptatyr has learned is apparently serious enough that he would rather allow Mimameith to die than continue pursuing the method.

That raises a far more disturbing possibility than simple scientific failure.

Perhaps the Crimson Moon’s power could have worked.

Perhaps the cost was the problem.

HoYoverse still does not completely explain what Hroptatyr saw or understood during that experiment, and the teaser carefully preserves that ambiguity.

A blessing and a curse may be separated only by their purpose

That ambiguity gives the official description of Bygone Days considerably more weight.

HoYoverse explicitly asks players to consider how “blessing” and “curse” are born of the same essence.

The immediate interpretation is difficult to ignore.

The ability to extend somebody’s life can be viewed as a blessing when the person being saved is dying. But Genshin Impact has spent years establishing that forced immortality can also become one of the most horrifying punishments imaginable.

Khaenri’ah itself is the clearest example.

After the Cataclysm, survivors were subjected to supernatural consequences that included the Curse of Immortality, leaving figures such as Dainsleif alive for centuries while their bodies, memories and identities were gradually consumed by time.

The new teaser does not explicitly say that Hroptatyr’s experiment and that later curse are identical processes. Treating them as definitively the same would go beyond what HoYoverse has currently confirmed.

But the thematic connection is deliberate.

A power capable of preventing death can be salvation when freely given to someone desperately seeking more time. The same principle becomes a curse when death is denied indefinitely.

The difference may not lie in the power itself.

It may lie in how that power is used.

Mimameith dies and the friendship effectively dies with her

Whatever possibility Hroptatyr discovered is never used to save their professor.

Mimameith dies.

Bygone Days closes that part of the memory in a cemetery beneath heavy rain and mist, replacing the bright flowering garden of the earlier scenes with an environment almost completely drained of warmth.

Eftirvit comes to her grave.

Hroptatyr is there as well.

But the two men no longer behave like the friends shown earlier.

Hroptatyr eventually leaves beneath his umbrella, while Eftirvit remains behind with the person they had once hoped to save.

There is no dramatic duel, no declaration that they are now enemies and no catastrophic magical explosion separating them.

That restraint is what makes the scene effective.

Their relationship appears to end through something much more believable: grief, anger and the realisation that one person can no longer trust the other.

The knowledge Hroptatyr refused to share becomes the space between them.

Hroptatyr’s later title makes the memory considerably darker

Players already know where Hroptatyr’s obsession with knowledge eventually leads.

He becomes President of the Universitas Magistrorum and Khaenri’ah’s Chief Royal Mage, receiving the formal title “The Wise.” He also becomes one of the Four Pillars associated with the kingdom’s highest levels of power and influence.

His defining desire is limitless knowledge.

That desire ultimately contributes to his fall.

During the events surrounding Khaenri’ah’s destruction, Hroptatyr joins the group later remembered as the Five Sinners of Khaenri’ah, alongside Vedrfolnir, Rhinedottir, Surtalogi and Rerir.

These individuals gain extraordinary powers while their homeland moves toward catastrophe, yet fail to save the nation when it needs them most.

The contrast with Bygone Days is striking.

Here, Hroptatyr is not yet an almost mythological Sinner.

He is a young scholar attempting to save his teacher.

That makes his eventual transformation more interesting because HoYoverse is no longer treating the Five Sinners simply as ancient superhuman antagonists. Recent Archon Quests have increasingly shown who these people were before history reduced them to titles.

They had friendships.

They had mentors.

They made choices gradually.

And in Hroptatyr’s case, the path toward limitless knowledge may have begun alongside a moment when knowledge frightened him enough to stop.

Eftirvit’s future gives the story another layer of tragedy

The other side of the friendship is equally significant.

Eftirvit would eventually become an important figure within the Universitas Magistrorum himself, serving as its Vice-President while Hroptatyr occupied the presidency.

But history remembers him by another identity.

Pierro.

The Jester.

The first of the Fatui.

The figure responsible for gathering the Fatui Harbingers beneath the Tsaritsa and one of the central architects behind Snezhnaya’s long conflict with the established order of Teyvat.

Pierro has always been closely tied to Khaenri’ah’s destruction. Earlier lore established that he attempted to warn the nation’s rulers about the danger approaching them but failed to earn the recognition necessary to prevent the disaster.

Bygone Days now adds another failure to his past.

Before losing his nation, he lost his teacher.

Before becoming separated from the civilisation he once served, he lost his trust in one of his closest companions.

And the person standing on the opposite side of that divide would eventually become one of the very Sinners associated with Khaenri’ah’s fall.

That context gives Pierro’s modern actions a more complicated foundation than simple revenge.

HoYoverse is slowly replacing mythology with people

For years, Khaenri’ah existed primarily as Genshin Impact’s great historical catastrophe.

Players knew about the destruction 500 years ago, the cursed survivors, Dainsleif, the Traveler’s sibling, the Abyss Order and the mysterious Sinners. But most of its major players were titles rather than characters.

The Snezhnaya storyline is rapidly changing that.

Version 7.1 continues placing faces, conversations and personal relationships behind events that once existed only as lore entries. Hroptatyr becomes more than “The Wise.” Pierro becomes more than “The Jester.” Rhinedottir, Vedrfolnir and the other survivors of that era are increasingly being positioned as participants in a tragedy whose causes were far more complicated than one kingdom simply being destroyed by divine judgement.

Bygone Days is particularly effective because it shows the catastrophe beginning long before the Cataclysm itself.

A civilisation does not necessarily fall in a single night.

Sometimes the first fractures are much smaller.

A dangerous experiment.

A hidden truth.

A dying teacher.

Two friends who stop trusting one another.

The past of a sinner may matter more than his eventual crime

The teaser’s central mystery remains unresolved.

What exactly did Hroptatyr understand when the Crimson Moon experiment failed?

Why was he willing to abandon a potential method of saving Mimameith?

And how does that knowledge connect to the later relationship between life, death, immortality and the curses imposed upon Khaenri’ah?

HoYoverse has provided enough information to establish the importance of those questions without answering them outright.

That restraint matters because Hroptatyr’s story is clearly not finished.

The player already knows what he eventually becomes. What Genshin Impact is now exploring is why.

Bygone Days therefore works less as an isolated lore video and more as another missing piece in the reconstruction of Khaenri’ah. It reveals that one of the Five Sinners once confronted a power capable of blurring the distinction between salvation and punishment — and that one of Pierro’s oldest wounds may have been created by the man who later embodied Khaenri’ah’s insatiable pursuit of knowledge.

The Mirror of Remembrance shows only the past.

But with the Five Sinners becoming increasingly important to Genshin Impact’s present-day story, the consequences of that past are no longer safely buried 500 years ago.