Kizuna AI — Epic Seven Fire Soul Weaver: RTA Build, Counters & Win Rate

Kizuna AI is a 4-star Fire Soul Weaver support whose entire kit scales off her own max Health rather than Attack. Her first skill fires a single-target heart that deals HP-based damage while cleansing one debuff from an ally, and her passive heals the lowest-Health ally at the end of every turn, again proportional to her max Health. Her third skill is the centerpiece: it shields the whole team with a 3-turn barrier and grants buffs, then speeds herself up for two turns, on a four-turn cooldown. She is a sustain-and-protection anchor who keeps allies topped up and warded rather than a damage dealer.

Counters

Damage-over-time and debuff-stacking teams — Her first skill cleanses a debuff from an ally every single turn with no cooldown, and her passive heals the lowest-Health ally at the end of each turn, so poisons, bleeds, and piled-on debuffs get stripped and the chip damage gets undone before it adds up.
Control comps that lean on stuns, silence, and slows — The recurring single-target cleanse can lift a stun, silence, or other crowd control off a key ally turn after turn, letting the team keep acting through lockdown attempts.
Burst and wide-hitting attackers — Her third skill blankets the entire team in a Health-scaled barrier for three turns, soaking the opening burst and cushioning multi-target swings so allies survive long enough to answer back.
Defense-break and HP-scaling bruisers — Constant end-of-turn healing plus team barriers blunt the steady, big-number damage those threats rely on, out-sustaining their attrition while she carries no fragile damage trade of her own.

Countered by

Buff stealers and buff strippers — Her protection plan is the team barrier and her self speed-up; an enemy that dispels or steals those buffs erases her contribution and can even turn her speed boost against her.
Buff-duration reducers — Her barrier lasts three turns and her self speed-up only two, on a four-turn cooldown, so shortening those durations leaves a coverage gap she cannot refill until the skill comes back up.
Unhealable inflictors — All of her sustain is healing scaled off max Health; an enemy that blocks healing shuts off her passive recovery entirely and reduces her to barriers and cleanses alone.
Pure offense that ignores her low threat — She deals only chip single-target damage and brings no crowd control or damage debuffs, so a fast attacker can simply race past her support and delete an ally before her end-of-turn heal or next barrier lands.

Who counters Kizuna AI? — full guide ›

Skills

S1Aitan Beeeam! ☆

Attacks by firing a heart at the enemy, before dispelling a debuff from an ally. Damage dealt increases proportional to the caster's max Health.

Soulburn −10 soulsDispels a debuff from all allies.

PCrisis Avoidance ♪

Recovers Health of the ally with the lowest Health proportional to the caster’s max Health at the end of the turn.

S3Super Intelligent AICD 4

Cheers on allies, granting a barrier (proportional to the caster’s max Health) to all allies for 3 turns, before granting increased Speed to the caster for 2 turns.