Number 6/Relationships

Knuckleduster
Number 6 has great respect for Knuckleduster when he was the hero O'Clock, to the point that he has a huge poster of him in his apartment. When he was still an experiment he watched when O'Clock's career fell apart and lost his Quirk. His admiration is such that his characteristic scar on his face is self-inflicted, as a tribute to the one that Knuckleduster has. He is so proud of this scar that he can not bear to have another injury on his face. His goal is to become the true successor to O'Clock, considering multiple possible names for himself, including: "O'Clock II" or "Two O'Clock".

Knuckleduster had no relations with him before investigating the Villain Factory. He doesn't know who he is or what his origin is, except that he is an agent of the Villain Factory and that he is in possession of his stolen Quirk Overclock. When they finally meet in person, Knuckleduster considers him nothing more than a villain, one that he plans to eliminate, so when Number 6 asks him to recognize him as his successor he flatly refuses. Despite being enemies, and having no qualms about killing him, Number 6 considers Knuckleduster the best one, much better than the Pro Heroes, even All Might.

Koichi Haimawari
At first, it is implied that Number 6 feels somewhat jealous of Koichi due to being Knuckleduster's disciple. Years later, Number 6 planned to frame Koichi in order for the tale of O'Clock II to become popular, only to be foiled by underestimating Koichi's Slide and Glide Quirk. As a result, Number 6 is indirectly charred by Endeavor's flames while Koichi escapes via flying, and 6 calls him a cheating bastard as he gets burnt.

Number 6 proceeds to then follow and talk to Koichi on a rooftop, where he explains his past as a "creation" and how he doesn't have a clue to what he is. He proceeds to state that while his body is fake, his rage and anger towards Koichi is genuine and real. Number 6 rants about how Koichi is garbage that only ruins other people's dreams, and swears revenge on him and Kazuho for ruining his plan.

Kazuho Haneyama
When posing as Rokuro Nomura, the manager of FeatherHATS, Number 6 begins to relate to Kazuho, ​​first on a purely professional level and then on a more personal one. Although initially Number 6 only did it to watch over and spy on Knuckleduster's allies and to meet his own goals, he developed feelings for Kazuho. Number 6 crafted Rokuro's personality to be supportive, kind and caring towards Kazuho, in order to get she to like him, and when he thought the time was right, he confessed his feelings to her, yet Kazuho kindly rejected them.

He takes Kazuho's rejection pretty hard, and for the next time he met Kazuho again, he lured her into an abandoned building to be parasitized by the Queen Bee, transforming into the new Kuin Hachisuka.

Endeavor
Endeavor knows of Number 6's hero persona, O'Clock II, though has never been formally introduced. The Flame Hero was deployed to stop the battle between Queen Bee and the Crawler, which was secretly incited by the fake pro. Fearing his powerful reputation, Number 6 hid himself away from Endeavor. Unaware of Number 6's presence, Endeavour accidentally gave the villain severe disfigurement in hellflame's crossfire. Despite this, Number 6 is initially indifferent towards Endeavor, consumed by his vendetta for the Crawler instead.