Yusai

Yusai is a master of the Moonlight-Style Iaijutsu sword school and a highly skilled fighter even among Negators.

She first appears in the recollections of Kuuno Akira as the former sword instructor of Andy, later reappearing as an elder member of the organization UNDER and, in a new loop, in her youth as a powerful ally of Fuuko Izumo’s group.

She is ranked fifth in the internal hierarchy of UNDER in the previous loop.

Despite her ability preventing her from drawing her sword, she turns this handicap into strength and remains one of the most formidable combatants in the story.

Her voice actress in the anime adaptation is Sumire Uesaka.

Official bonus material lists her birthday as October 21.

Name: Yusai

Gender: Female

Birthday: October 21

Affiliation (previous loop): UNDER

Affiliation (current loop): Union (Fuuko’s organization)

Appearance in the Main Timeline (Elder Yusai)

In the main timeline’s present, Yusai appears as an elderly woman with the air of a traditional samurai.

She has long silver hair tied in a single low ponytail around the nape of her neck.

She wears a kimono and covers her head with a straw hat shaped like a woven conical hat.

Even in old age she is described as a considerable beauty, with a dignified, calm presence befitting a veteran swordmaster.

Appearance in the New Loop (Young Yusai)

In the new loop, Yusai returns in her youth, looking much like she did in Andy’s flashbacks.

This younger version no longer wears a straw hat and instead fights in traditional Japanese clothing with bandages wrapped around her chest.

Her hair is tied in a ponytail and she carries a white scabbard at her waist.

She is often seen tipping up a gourd to drink from it; the contents are unclear, but she does not appear drunk.

Her features are clearer and sharper than in her elder form, giving her more of a “handsome beauty” or androgynous elegance than a soft, cute type.

Later, after joining the organization, she wears the standard suit-style uniform, using the common red tie as a hair tie for her ponytail.

Personality as an Elder

As an elder, Yusai is calm, disciplined, and deeply committed to the way of the sword.

She lives in a remote mountain area somewhere in Japan, acting as the master of Moonlight-Style Iaijutsu.

In Kuuno Akira’s flashback, she appears as a strict yet warm teacher to Andy.

When Andy masterfully learns her Iaijutsu technique “Eigetsu,” she is moved by his talent and asks him to stay with her.

She blushes while hinting at wanting him as her successor and even talking about a future together, revealing a girlish, romantic side beneath her stoic exterior.

When Andy refuses her due to his immortality and their difference in lifespan, she hides her eyes under her straw hat and quietly sheds tears.

Like Gina Chamber, she is one of the women who harbor a bittersweet, unrequited affection for Andy.

Even so, she does not cling to him, and her affection is expressed more as longing and regret than obsession.

In the main story’s Spring battle, she appears as an elder swordswoman following Billy Alfred as part of UNDER.

When Andy infiltrates UNDER through Fuuko Izumo, he refers to Yusai as “basically an ex-girlfriend,” hinting at the emotional weight of their shared past.

Personality in the New Loop (Young Yusai)

In the new loop, Yusai’s core goodness remains, but her youth gives her a more energetic and bold demeanor.

She is portrayed as a hearty, big-hearted woman, a “heroic female warrior” type rather than a quiet elder.

She embodies perseverance and unshakable resolve: even after gaining a power that prevents her from drawing her sword, she does not despair.

Instead, she starts over from scratch, training herself to fight effectively despite this overwhelming handicap.

At the same time, her still-developing control over UNDRAW leads to comical moments in daily life.

Chopsticks she holds in her mouth or the gourd between her teeth sometimes get stuck and will not come out, leaving her with a slightly goofy expression.

Because she is beautiful, even these clumsy, frozen-mouthed moments are more charming than embarrassing.

These little incidents also underline that many Negators suffer from inconvenient side effects in everyday life, not only in battle.

There are hints that her condition can be improved: for example, the chopsticks may come free if she opens her mouth wide while talking.

This suggests that, through experience and better understanding, she might learn to manage her ability more precisely over time.

Negation Ability: UNDRAW – “Un-Draw” / “Un-Pluck”

Yusai’s negation ability is UNDRAW (Unbatsu / Un-Pluck), the power to deny the act of pulling out, removing, or extracting.

In effect, whatever is targeted cannot be drawn, pulled free, or removed once the ability is applied.

The exact activation conditions are not fully explained, but it is implied that the ability can affect both herself and others, as well as various objects.

Because she is a master swordswoman, this has a cruel twist: the scabbard and blade she carries can no longer be drawn in the traditional sense.

She is therefore a warrior who, despite being a master of sword drawing techniques, bears the burden of an ability that forbids her from drawing her sword.

Rather than surrender to this limitation, she faces it with an unshakable determination and adapts her style around it.

In her elder period, she has honed her skills to an exceptional level even with this restriction.

During the battle against Spring, she uses her ability to prevent cherry blossom petals from falling by denying their “dropping” or “falling away,” effectively holding them in place.

This same principle is what traps objects like weapons, body parts, or even monsters’ limbs, preventing them from being pulled free.

Her resolve in the face of this ironic power is likened to the expression “unshakably firm,” capturing her mental strength.

Combat Style with UNDRAW (New Loop)

In the new loop, Yusai is at her physical peak and is an absolute powerhouse in terms of combat strength.

Even though UNDRAW prevents her from drawing her blade, she uses her scabbard alone as a weapon.

With just the scabbard, she can cleave a monstrous UMA in half and crush or twist several tanks at once.

These feats demonstrate that her raw physical skill and refined technique are so extreme that the lack of a drawn blade hardly feels like a disadvantage.

At this stage, she is still learning the finer mechanics of UNDRAW.

Through missions and battles alongside Fuuko’s group, she gradually expands her practical experience and improves her ability control.

Her style blends precise Iaijutsu posture with brutal, creative use of the scabbard as both blunt weapon and seal.

She can also use UNDRAW to immobilize enemies by making their limbs or embedded bodies impossible to pull free from the terrain.

Past Relationship with Andy

Long before the main events, Yusai lived as a swordmaster deep in the mountains of Japan.

Andy sought her out and trained under her, learning Moonlight-Style Iaijutsu.

She taught him the Iaijutsu technique “Eigetsu,” a cutting move strong enough to mow down surrounding trees in a single test slash.

At that time, she still used a normal scabbard and blade rather than stabbing a sword into her own arm, which Andy later develops into his unique “Regeneration Draw” technique.

Deeply impressed by Andy’s progress, she grows emotionally attached to him.

She begs him to remain by her side, even blushing as she refers to matters of succession and hints at a shared future.

However, Andy rejects this, citing his immortality and the difference in their lifespans as his reason.

Yusai accepts this painful truth in silence, hiding her eyes under her straw hat as quiet tears fall.

This heartbreak sets the tone for their relationship: a teacher who once loved her student, and a man cursed with immortality who cannot easily commit to anyone.

Later, when Andy hears about Yusai from Fuuko, who has infiltrated UNDER, he casually calls her “pretty much an ex-girlfriend,” acknowledging their complicated bond.

Yusai in UNDER (Previous Loop)

In the main loop prior to the reset, Yusai appears again as an elderly swordswoman working for UNDER.

Within UNDER, she holds the fifth seat in the organization’s internal ranking, highlighting her high status and power.

She serves under Billy Alfred and participates in the Spring battle as part of UNDER’s forces.

During the confrontation, she briefly crosses swords with Andy, who is trying to retrieve Fuuko Izumo.

Her involvement as a former ally of Andy now standing on the opposite side adds emotional tension to the conflict.

It also demonstrates how the cruel structure of loops and fate can twist people’s paths, turning once-close figures into enemies or rivals.

The Loop System and Yusai’s New Chance

The world of Undead Unluck is governed by a special “Loop” system, in which the entire world is destroyed and recreated repeatedly.

By the start of the main story, the world has already gone through its 100th cycle of destruction and rebirth.

Yusai, like many others, is affected by these loops.

In the new loop triggered later in the story, Fuuko and her allies aim to save those who met tragic fates in previous cycles, including Yusai.

Their goal is to negate Yusai’s previous tragedy within UNDER and recruit her as a comrade instead.

This version of Yusai appears earlier in her timeline, still in her youth and already awakened as a Negator.

First Appearance in the New Loop

In the new loop, Yusai is first seen defending a village with which she has deep personal ties.

She stands against a spiky UMA whose limbs are embedded into the surrounding terrain.

Using UNDRAW, she prevents the UMA’s limbs and body from being pulled free, pinning it in place for an entire week.

By the time Fuuko arrives, Yusai is on the brink of starvation, having held the line alone for days.

Fuuko rescues her from this desperate situation and explains the broader conflict and the nature of their organization.

Grateful to Fuuko for saving both her and the village, Yusai readily agrees to join as a comrade.

From that point on, she participates in missions, gradually turning her once-cursed-seeming ability into a powerful asset for the team.

Her inclusion in the group represents the successful “negation” of the tragic path she followed in the previous loop.

Moonlight-Style Iaijutsu and “Eigetsu”

Yusai is the master of Moonlight-Style Iaijutsu, a sword technique focused on drawing and cutting in a single motion.

Her signature move as a teacher is the technique known as “Eigetsu.”

When Andy trains under her, she teaches him this move using a normal sheath and blade.

In testing, a single stroke of Eigetsu is powerful enough to fell several surrounding trees in one swing.

Andy later adapts this Iaijutsu into his own style by stabbing his sword into his limb and using his Undead regeneration to perform “Regeneration Draw.”

This evolution shows how deeply Yusai’s teachings influence Andy’s combat style and growth as a fighter.

Combat Feats

Even without drawing her sword, Yusai’s combat achievements are extraordinary.

In the new loop, she is shown slicing a UMA with just her scabbard and violently distorting multiple tanks in an instant.

During the Spring battle in the previous loop, she uses UNDRAW to manipulate the environment, such as fixing cherry blossom petals in the air to prevent them from falling.

She can immobilize enemies or objects by making it impossible for them to be pulled free, creating battlefield control that few can counter.

These feats underline that her reputation as an elite fighter is built on both raw skill and clever use of her negation ability.

Her entire style exemplifies overcoming limitations: she turns the inability to draw her sword into the core of an unconventional, devastating technique set.

From the circumstances under which young Yusai is found in the new loop, we can infer the tragedy that likely befell her in an unaltered timeline.

If Fuuko and the others had not intervened, Yusai might have failed to fully harness UNDRAW’s potential in time.

In that scenario, the UMA could have eventually freed itself or bypassed her defenses, attacking and destroying the village she tried to protect.

This failure to save her people with the very power meant to protect them would have defined her “Negator’s tragedy.”

The new loop, however, grants her a chance to deny that outcome.

By joining Fuuko’s organization, she moves forward as an ally, working to protect others and grow stronger alongside comrades who understand her burden.