Kosaku Kawajiri (Yoshikage Kira) is included in the base game as the main antagonist of Part 4. In-game, he is consistently labelled "Kosaku Kawajiri" to differentiate him from his previous form. Kosaku Kira has 1000 HP.
Along with Enrico Pucci, Hol Horse, Johnny Joestar, Koichi Hirose, and Giorno Giovanna, Kosaku is a character who can utilize more than one Stand during a match as part of his moves; He retains Killer Queen, but exchanges some powers like Sheer Heart Attack for access to Stray Cat, who assists him in battle with its air bubbles.
Costumes
Kosaku Normal
Kosaku Costume A
(Chapter 370)
Kosaku Costume B
(Chapter 377)
Command List
Killer Queen may not have more than one bomb out at a time. If Kosaku performs any skill that would create a new bomb, any existing bomb is overwritten and nullified.
ON GROUND Kosaku can summon or dismiss Killer Queen, shifting his available abilities.
+ 
ON GROUND WHEN DOWNED
(Stand On only)While the opponent is down, Killer Queen appears and stomps on them.
Though this move is identical to the original Kira's "It's your fate to be defeated" skill, its name implies it to be the stomp Killer Queen attempted to use on Stray Cat during their first encounter.
+ 2 ATK Buttons ON GROUND Kosaku immediately detonates whatever bomb may be out at the moment. The explosions of all of Kosaku's bombs cannot be blocked, but Kosaku himself is at risk of taking damage if he is too close to the blast.
+ 
//
ON GROUND Kosaku summons Killer Queen and Stray Cat to fire an air bomb that is manually controlled and detonated, Kosaku himself remaining stationary. The size and damage of the air bomb created is determined by the attack button inputted, though its speed is inversely affected. These bombs deal higher damage than Contact Bombs, are unaffected by opposing attacks, projectiles, and traps, and produce large explosions that cannot be jumped over. However, Kosaku cannot act while he is controlling the air bomb, and the bomb disappears as soon as he is hit.
+ 2 ATK Buttons ON GROUND With his mental math skills, Kosaku can manually correct the trajectory of an in-flight Impact Ignition Bomb should the opponent have moved out of its path, instantly changing its direction in order to once more send it in their direction. Doing so shrinks it by one level, reducing its explosive power but increasing its speed. A Light () bomb's trajectory can be changed only once, while a Heavy () bomb's trajectory can be changed up to three times.
+ // ON GROUND Kosaku summons Killer Queen to rush forward in a barrage of punches, pushing the opponent away and knocking them down. Although this move is a punch rush-style of attack, Kosaku cannot actually initiate Rush Mode, and a similar move by other opponents will easily overpower Killer Queen. (Flash Cancel comboable)
+ // ON GROUND Killer Queen fires an air bomb that will automatically explode on-contact with the opponent, requiring no manual detonation and allowing Kosaku to move after a short recovery period once launched. The speed of the bomb created is determined by the attack button inputted. The bomb is able to disarm traps, but is popped by all other projectiles aside from another Kosaku's own Contact Bomb. (Comboable).
A Stand Rush skill that Kosaku can disconnect from to freely act while it is executing, including moving away from the bomb. However, Killer Queen remains at risk of being caught in the explosion if Kosaku uses Stand Rush in an attempt to escape a close-ranged blast. (Flash Cancel comboable)
+ // ON GROUND WHEN DOWNED Killer Queen channels its power into its index finger before chopping downward. If the opponent is hit, they themselves become a bomb. Kosaku can then detonate the opponent at any time, including when they're on the ground, dealing heavy damage. A Stand Rush skill that Kosaku can disconnect from to freely act while it is executing. (Flash Cancel comboable)
x2 + // ON GROUND TRAP Killer Queen places a small stone primed with the first bomb in front of Kosaku on the ground. The stone must be manually detonated and sends the opponent flying far away from Kosaku if they are caught, giving him more room to unleash air bombs.
+ // ON GROUND Stray Cat creates an air bubble acting as a passive cushion in Kosaku's suit. This protects him from the next High/Middle attack from the opponent, pushing them away if they trigger it with a melee strike and allowing Kosaku to power through the attack uninterrupted. The air cushion is cancelled if Kosaku dismisses Killer Queen.
ON GROUND Kosaku grabs the opponent and explodes them in his hand as he lightly throws them.
+ 2 ATK Buttons ON GROUND A counter. Killer Queen exposes Stray Cat and moves in front of Kosaku, resulting in an air bubble cushion being created. If Killer Queen is struck with a non-Throw/HHA/GHA melee attack, the opponent will be repelled and knocked to the ground. Kosaku will take the opportunity to send out the completely invisible air bubble towards them, now primed as an air bomb. Using his math knowledge, Kosaku correctly predicts where the air bomb is and detonates it at the right moment, blowing his opponent up.
+ 3 ATK Buttons, or 
ON GROUND Kosaku brings out Hayato with Killer Queen's Third Bomb attached to him, who then then runs away in fear with Killer Queen following closely. If Hayato bumps into the opponent, they will be stunned by his sudden interference as he begins to panic, only for them to see Killer Queen in their left eye. The Stand promptly detonates its third bomb, initiating a temporal loop as Kosaku gleefully celebrates the bomb's success.
This GHA inflicts the lowest damage of any in the game, dealing only ~21% of the opponent's health in damage, and making it inferior even to his HHA in damage output. Not unlike with Sheer Heart Attack, Bites the Dust is unblockable, but is easily dodged/sidestepped/jumped over, and Hayato will only run a short distance in front of Kosaku before suddenly sprinting the other way and off the battlefield.
However, if successful, this GHA adds 10 counts to the battle timer and restores ~15% of Kosaku's health. Kosaku and his opponent are also reset to their round-start positions. In addition, the time-looping effect uniquely allows Bites the Dust to reverse a number of character-specific effects, including any round- or match-lasting abilities.
- Jonathan Joestar: If Jonathan has activated his "This is my final Ripple!" comeback ability and recovers, its passive effects will be undone and access to his HHG will be restored to him as well.
- Kars: If Kars has evolved into the Ultimate Thing using his GHA, his transformation will be undone and the Heart Heat spent will remain lost.
- Giorno Giovanna: If Giorno has Gold Experience in Requiem Mode using his GHA, the transformation will be undone and the Heart Heat spent will remain lost.
- Enrico Pucci: If Pucci has evolved his Stand into C-Moon or Made in Heaven, it will be reverted all the way back to Whitesnake. In MiH's case, the stage will also revert back to what it was previously, and Pucci will be unable to enter Made in Heaven Mode again for the rest of the match as per his own gameplay rules. If his Stand was still Whitesnake, any of the 14 words already spoken to the Green Baby will be cleared.
- Johnny Joestar: If Johnny has Tusk evolved into any Act beyond ACT1, including ACT4, then the Stand will be reverted back to ACT1 and Johnny's available abilities will be reverted accordingly.
- Funny Valentine: If Valentine has used his "Back from the 'other side'" skill, access to his HHG will be restored to him.
When low on health (Rumble Mode), instead of calling out the bomb's name, Kosaku will fiercely yell "This is the limit! Push it!".
Gameplay Overview
Kosaku is a "zoner"-style character utilizing both Killer Queen and Stray Cat. With good normal attacks, a counter HHA, and his unblockable and versatile air bombs, he can make his opponent hesitant to attack. An individual air bomb creates large explosions inflicting devastating single-hit damage. Said explosions linger for considerable amount of time, and Kosaku can utilize this trait against an opponent recovering from knockdown, detonating air bombs over them as they get up to catch them in repeated unblockable explosions. Even when threatened by a close-ranged foe, he has abilities, such as Killer Queen's other bombs, that are useful for creating much-needed distance. Above all else, his unique GHA both replenishes his health and can potentially turn the tide of battle by undoing his opponent's passive abilities and powered-up states.
However, Kosaku is innately high-execution and high-risk. His most notable combos and offensive setplay involve closely following behind Contact Bombs that place him at risk of self-inflicted damage, even requiring he Stylish Evade his own explosions. Due to the relative predictability of air bombs, Stylish Evade is also his greatest weakness and opponents that can execute the ability consistently can trivialize their power. In addition, Kosaku struggles against fellow zoner types; Fast projectiles can interrupt Impact Ignition Bombs and pop Contact Bombs, ultimately forcing him to be the aggressor.
Kosaku is a technical character whose strange techniques belie a wealth of lethally powerful unblockable attacks, leading to constant high-damage and Heart Heat gain. Maintaining good spacing from the opponent to keep himself safe naturally grants him many opportunities to unleash his deadly bombs. When combined with multiple defensive and reversal abilities including Bites the Dust, Kosaku can quickly compound small advantages into assured victory.
Story Mode
Diamond is Unbreakable
(杜王町の怪物 Moriō-chō no Kaibutsu)
2. Block a projectile with the "He heals pretty quick!" skill. (1000 G)
3. Use the "As you were!" skill. (1000 G)
Kosaku: All I want is peace. Battle is the exact opposite of that. I hate it.
(黄金の精神 Ōgon no Seishin)
2. Land "Meet my 'homing missile!'" from a Heart Heat Attack. (1500 G)
Kosaku: Hmm. I should aim to avoid close quarter combat with Crazy Diamond.
(杜王町の怪物 Moriō-chō no Kaibutsu)
2. Land the "I'll have to fight it out!" skill. (Stray Cat Killer Queen 3D Model)
Kosaku: All I want is peace. Battle is the exact opposite of that. I hate it.
(黄金の精神 Ōgon no Seishin)
2. Use the "Trajectory Change" skill. (1000 G)
3. Land a Heart Heat Attack. (1500 G)
Kosaku: Hmm. I should aim to avoid close quarter combat with Crazy Diamond.