All-Star Battle ★ Koichi Hirose
Koichi makes his playable debut in the PS3 game and was confirmed along with Akira Otoshi. Koichi is voiced by Romi Park, who previously voiced Giorno Giovanna and Gold Experience Requiem in the aforementioned PS2 GioGio game.
As one of the majority of playable characters with the "Stand" Style, Koichi can turn Echoes ACT3 on/off, changing movesets, as well as having access to the Stand Rush ability returning from the Capcom game, being able to attack in conjunction with his Stand. Along with Enrico Pucci, Kosaku-Kira, Johnny Joestar, Hol Horse, and Giorno Giovanna, Koichi is a character who can utilize more than one Stand during a match as part of his moveset. In gameplay, Koichi uses all three forms of Echoes as part of his moveset, unlike Johnny or Pucci, who need to evolve their Stands during combat. Koichi has 900 HP.
Costumes
Koichi Normal
Koichi Costume B
(Chapter 297)
Command List
During a fight, Koichi can use several different abilities that were featured in Diamond is Unbreakable.
Koichi can summon or dismiss Echoes ACT3, shifting his available abilities.
+ 
Koichi lunges forward and swings a fist with all his might. If the punch connects, the opponent is knocked off their feet. This skill is a middle attack that cannot be blocked crouching. A command normal that can chain into Koichi's skills. (Comboable)
Koichi's HHA, GHA, or his "S-H-I-T" special skill will inflict 3 Freeze upon connecting with the opponent.
Under its effects, the opponent is made heavier due to ACT3's unique ability, and forced into a constant crouch. This results in them being unable to dash, jump, or utilize special skills, HHA, or GHA.
While the effect cannot be broken manually (hitting Koichi or gaining distance does nothing), it has a relatively short duration, slightly altered based on the attack that generated it. Although the opponent is forced into a crouching state, they are still able to freely guard against all Middle attacks and will automatically stand to do so when defending.
+ 
/
/ Koichi summons ACT1 to fly forward a moderate distance and assault the opponent with loud and disruptive SFX. This move has a follow-up. (Flash Cancel comboable)
+ // ACT1 increases the number and volume of its SFX, causing the opponent to take damage multiple times until they collapse from the noise. (Comboable)
+ // ACT2 throws its tail end as a projectile SFX that arcs. The attack button inputted determines the projectile's arc and distance thrown. If it hits the opponent, they will catch fire and gradually lose health over time for a few seconds. This move functions as an anti-air. (Flash Cancel comboable)
+ // A counter. Koichi boldly crosses his arms and side-glares at the opponent. If they strike him during that moment, SFX by ACT2 will reveal itself on Koichi and produce a forceful explosion, blowing them back.
+ // ACT2 slaps an SFX on the ground in front of Koichi. The SFX acts as a Low-hitting trap that cannot be 'blocked' standing, and only one may be active at a time.
If the opponent comes in contact with it, they'll be blown upward into the air and land in a soft knockdown (Comboable). If Koichi himself steps on it, he will be sprung high into the air akin to a Super Jump ability, allowing him to evade many of the opponent's attacks or set up his own attacks from the air.
+ // ACT3 flies forward a moderate distance while rapidly punching, pushing the opponent away. (Flash Cancel comboable)
+ // ACT3 rises upward and comes down punching with the power of 3 Freeze active, knocking the opponent down. This skill is a Middle attack that cannot be blocked crouching, functions as an anti-air, can strike a downed opponent, and inflicts the 3 Freeze effect for a short duration. A Stand Rush skill that Koichi can disconnect from to freely act while it is executing.
Of note is that this skill will not lose its Middle-hitting property when Stand-Rushed, allowing Koichi himself to assail a defending opponent with crouching normals while ACT3 simultaneously attacks from above, resulting a high-low offense that is difficult to defend against. (Flash Cancel comboable)
+ /// ACT3 swiftly moves in front of Koichi and unleashes a potent burst of air that will knock both him and the opponent (if they're in range) back a long distance. This skill is a combo-breaking ability capable of interrupting an opponent attacking Koichi, and unlike other skills of its kind, does not cost any Heart Heat to perform. Instead, however, Koichi is self-harmed in the process for a substantial amount of extra damage, half of which is silver damage. Koichi may recover the silver health over time, but only if he does not receive any more damage again during the process.
Koichi shoves the opponent off-balance while ACT2 whips them with a "Whooosh!" SFX from its tail, sending them flying.
+ 2 ATK Buttons Koichi sends ACT3 flying forward a considerable distance, rapidly punching with the power of 3 Freeze active for an extended period of time. The opponent is pushed away, and the final hit will knock them down. Successfully landing the attack inflicts the 3 Freeze effect for a medium-length period of time.
This HHA does not require an initial hit to connect in order to work, and will not stop until it finishes or Koichi is interrupted.
+ 3 ATK Buttons, or 
Koichi first summons Echoes ACT1 to throw a "BAM!" SFX projectile forward. If it connects, the opponent is assaulted by booming SFX loudly repeating itself, forcing them to cover their ears. ACT2 opportunistically flies in and slaps a "KaBOOM!" SFX on the floor under them, blasting them skyward. Finally, ACT3 suddenly appears above the airborne opponent and charges up 3 Freeze, then assaults them with an intense barrage of punches. The final strike causes ACT3 to pass through the opponent, before they fall with increased gravity and smash harshly into the ground.
This GHA inflicts the 3 Freeze effect for a long period of time.
Gameplay Overview
Koichi is an unorthodox fighter who can wield Echoes's unusual array of powers for a variety of scenarios. Due to his notably small stature (bested only by Iggy as the smallest character), he can play highly evasively and avoid his opponent's attacks with ease. Juxtaposing this is his long-reaching normal attacks and skills that can extend far away from him, allowing Koichi to apply offensive pressure at mid-range. His skills when utilizing ACT1 and ACT2 focus on crude utility, offering more diverse specials to play defensively or in skirmishes. Meanwhile, ACT3's abilities are more simplistic and emphasize a close-ranged offensive playstyle, with the threat of 3 Freeze being a valuable tool as well as an readily available, if not punishing combo breaker.
Koichi's weaknesses come in his small size and the fluidity of his arsenal. His size makes him easier to juggle and thus combo, coupled with lower-than-average health can render him vulnerable to heavy damage. A rare negative quality of his is that his set of skills, while fine individually, lack cohesion. Koichi's moves seldom flow well into each other on offense, possessing poor 'hitstun' or launching effects unsuited for use in combos. This results in him being a rather mechanically awkward character who is more limited in combo potential and damage output than most.
In all, Koichi aims to play around his opponent's attacks, using his small size yet large attacks to outmaneuver and punish mistakes accordingly. While in effective range to use ACT3's strength, he can apply 3 Freeze to force the opponent on the defensive, opening up opportunities to freely assault them with little chance of them retaliating.
Story Mode
Diamond is Unbreakable
(漫画家のうちへ遊びに行こう Mangaka no Uchi e Asobi ni Ikō)
Rohan: Splendid! I bet all my readers are going to love your personality, too.
(殺人鬼を追え Satsujinki o Oe)
2. Use the "This air pressure?!" skill. (1000 G)
Kira: I shall reclaim the jacket with the button... after I dispose of you, that is!
(漫画家のうちへ遊びに行こう Mangaka no Uchi e Asobi ni Ikō)
2. Land a Great Heat Attack. (1500 G)
Rohan: Splendid! I bet all my readers are going to love your personality, too.
(殺人鬼を追え Satsujinki o Oe)
2. Land the "You bastard!" skill. (1000 G)
3. Land the "Calm and cool" skill. (1000 G)
Kira: I shall reclaim the jacket with the button... after I dispose of you, that is!
Trivia
- Koichi won the first place in his League Group in the All-Star Battle League, beating fan favorites such as Giorno, Jolyne, and Gyro. He even managed to reach to the semi-finals matches, but ultimately lost to Jotaro.
