Kenichi the Mightiest Disciple
Renka of Ryozanpaku
Chinese Invasion
When Ma Kensei is preparing to leave his family to run and hide in Japan, Renka (age 7) latches on and refuses to let her dear papa leave without her. When his wife hears of his plans due to Renka's very loud whining, she compromises with Kensei. She would take over for him as the Phoenix Alliance leader for a time to allow him the chance to travel and relax. In exchange, he has to bring Renka with him on his travels, no exceptions. Grudgingly, Kensei accepts these terms.
Years later, Renka (14) lives in Ryozanpaku with her father. She and Miu are tentative friends, regular sparring partners, and rivals in all things martial arts. Renka attends the co-ed public school while Miu goes to the all-girl school. Because of this, Kenichi is much more familiar with and attracted to Renka than any other girl. Her obvious skill with martial arts eventually drives him to follow her in hopes of learning where she studies, leading him to Ryozanpaku two years earlier than canon. Renka ambushed him when he did that, believing he was some kind of perverted stalker. But Hayato interrupted the beat down and, deciding that Kenichi would be a good student, decided to allow him to enroll in the dojo. Around the time that Kenichi becomes a fulltime disciple, Ragnarok begins to form and rise in power.
Renka and Miu both frequently butt heads over Kenichi, each trying to become his girlfriend. They usually resolve their momentary tempers with fierce spars that leave one or both in bloody heaps and needing Akisame and Kensei to patch them up. These spars cause both to grow in skill rapidly, much to Kenichi's distress.
Seeing an opportunity to practice his skills of waging war and seizing power/territory, Niijima forms the Shinpaku Alliance with Kenichi unwillingly as his Assault Commander (with Miu and Renka as Captains) to counter Ragnarok. Niijima frequently has arguments with Renka over who's in charge of the Alliance and why. Niijima is also able to enlist Valkyrie, Thor, Siegfried, and (tentatively) Hermit in the Alliance after they're all beaten by Kenichi.
The Shinpaku and Ragnarok become fierce rivals as time passes. Neither Kenichi nor Ryuto care much for their gangs butting heads since they're more focused on training, but Kenichi does help out in the big battles to protect his friends. When Ragnarok begins losing momentum and members, Ryuto forced to step in and reassert his power, setting off a series of battles between him and Kenichi.