Kamikaze/Synopsis

Alien Conquerors Arc
Atomic Samurai first greets Bang, Genos, and Saitama enthusiastically as they arrive at the Hero Association meeting, although he notes that he does not know who Saitama is. Bang likewise acknowledges him and Saitama moves to shake his hand, which Atomic Samurai deftly denies, stating that he will acknowledge Saitama only when he has made it up to S-Class on his own.During the meeting, Atomic Samurai wonders if Bang will teach Saitama and Genos martial arts, thinking that they will make decent rivals for his own disciples. Later, after A-City and a would-be opponent Sky King are destroyed by the newly arrived Dark Matter Thieves, Atomic Samurai's disciple Iaian enters a skirmish with Melzalgald. After Iaian loses his left arm, Atomic Samurai intervenes by attacking the alien. Realizing the heavy wound of his disciple, he vows to not allow Iaian's swordsmanship to end in this tragic way.

Atomic Samurai then engages Melzalgald in combat alongside Bang, Metal Bat and Puri-Puri-Prisoner. During their fight against Melzalgald, Metal Bat exposes its weakness by destroying the vital marble that allows him to regenerate, thereby allowing the four S-Class heroes to successfully counterattack. However during the battle, Atomic Samurai is surprised to see Bang, who was caught off guard during his counterattack, get sent flying across the battlefield by a direct blow received from the monstrous alien. When Bang got up unhurt, Atomic Samurai slashed the monster and Bang destroyed the last marble inside. After the monster was defeated, the spaceship that was above them started to crash down. Atomic Samurai helped Iaian run towards the Hero Association Headquarters. Sweet Mask appears, demanding an explanation on why the city is in ruins. Atomic Samurai explains what happened, but wasn't good enough for Sweet Mask.

Monster Association Arc
Kamikaze attends a meeting of the Council of Swordmasters. At the meeting Atomic Samurai asks the council members for help in catching and killing Garou in worries that Bang might fail and die. The council members agree, except Haragiri who mocks Atomic Samurai's plea. Haragiri proceeds to show them the Monster Cells and reveals he had received them from the Monster Association and transforms into a Mysterious Being himself. Haragiri then orders the other to eat the cells or he will kill them, but Atomic Samurai cuts him first, killing him.

Original Webcomic
He accompanies the other S-Class heroes against the Monster Association. He gets defeated by Black Sperm.

Fall of the Hero Association Arc
Atomic Samurai talks with Bang about Bang's retirement. He is shown thinking about what he will do without Bang, and questions if he should try his luck with Saitama.

He is later seen in M-city looking for King for a duel, however, he cannot find him and proceeds to have sushi with his disciples. During the meal, he meets King at the restaurant and provokes him into a fight. After hearing the King Engine, he and his disciples mistakenly believe King is in battle-ready formation. During this time, King is choked because of fear, which is further misinterpreted by the others as boldness.

Fortunately for King, Kamikaze puts his sword down and praises King's boldness not before slicing an apple into pieces. After that, he forces King to go outside and begin to fight. However, during the fight, King begins to bluff nonsense about a non-existent atomic reaction, which confuses him and his disciples. At the end of his speech, King walks away and tells Kamikaze not to perform his attack since it can lead to casualty, something which the heroes don't want to happen. As the result, Kamikaze puts down his sword.

Despite that, Kamikaze urges King to cut an apple with his Katana to determine King's life and power. However, King is too nervous, scared, and weak to even pull the sword out of the sheath. As a result, King delays cutting the apple for several minutes and ultimately puts down the sword to walk away in shame. Fortunately. Kamikaze's delusions about King's reputation and power kick in and he incorrectly deduces that King cut the apple at the cellular level, faster than he can even see, stating that the apple "does not even know it has been cut."

In the end, Kamikaze praises King's fake power and asks his students to join him in honing their swordsmanship in basic training since he thinks he needs to practice more in order to surpass King. Meanwhile, King walks away in shock and anguish.