Hmm Aki would probably either join because a big price is promised to the winner or she has a mission to search for someone. Meanwhile if it's a story like P4 arena, she would probably uncover some mysteries of the tournament on accident and also have a clash again with her shadow. So probably join out of profit, but learn more about herself.^^

I don't know if Eito is good enough to be an actual fighter. Maybe an announcer or support character tho. If he did get a story mode, he'd probably enter for money or out of some strange curiosity to learn everything he can about all this stuff.

If Star had her own story... she'd probably be after the main Villain for causing trouble and to fight a much stronger clone of herself. So...her whole character arc is her trying the stop the villain and save the day, but have fun with it like normal. Also her own reason of fighting of a clone of herself because she's fucking bored.

(note: I'm Shadowgear. This is a dedicated RP account. even though i barely rp) Kamui's story starts as he tries to solve a conflict between two students at Byakusogen. Eventually, he finds out there's something big going on, and joins in. Depending on if the Final Boss was beaten with or without Judge Mode, the ending is different: -Without Judge Mode, the Final Boss is left alive so they can atone for their sins. Kamui returns to Byakusogen and tries to find a way to control Judge Mode. -With Judge Mode, the Final Boss is accidentally killed. Kamui decides to roam the world so he can't hurt people, and no one hears from him again...

Sam would likely only be in the fighting tournament (Assuming that's the overarching plotline) out of sheer curiosity. He would likely be apart from others, just wandering around getting involved with fights while trying to figure out what is going on. His final boss would be Machin Raal, who would probably be aiding the big bad in some way.

Jason would most likely find a portal after stealing Shinigami artifacts, (He a Shinigami thief) and it would lead to the tournament. His first opponent would be his Shadow, and be one of his rivals. But his Shadow would only appear twice. Once at the start, and once before Jason's final boss. His main rival(s) would be a switch between Rom and Shadow Rom. His final boss would be Garrett, the Shinigami who gave him his thieving powers.

Rom's story would likely be about entering the fighting tournament to accomplish two of his main goals: Investigate and destroy the cause of his Sinnesloschen abilities reappearing after getting a lead on a certain someone's appearance into the nexus, and to improve his fighting prowess in general. His rivals would be Jason (friendly), Sam (friendly), and Shadow Rom. His final boss would be a man who goes by the name of Sakujo, the source of the anomaly inside of Rom, and likely also assisting the big bad in some way.

Heart/Mot'Aru's story would probably be something where they get enough power to regain their true form, then rampage across the Nexus and slowly consume all the fighters in each stage. These fights will probably be rather difficult, and against higher-tier characters such as Star, Kalib, etc. The final fight will probably be against someone like Tatsuya, or a team of powerful characters. The ending will be bringing the entire Nexus under their powerful mind control.

Ina would probably just join the tourney because she wants her fire powers to grow stronger. She would fight characters with mainly firs skills, the final boss being either a corrupted Marisa, corrupted Star, or corrupted Senri, who has been corrupted by the big bad.

Sophia's story would probably be her being neutral until she's dragged into this mess purely out of curiousity. After that, she sees this as an oppurtunity to try and follow the villains out of spite, because of how much of a bad first impression she's had with heroes. Throughout the story however, she slowly gains more and more power as she fights against the good guys, with the choice of of fighting against someone like Tatsuya or Senri to be one herself, or fighting against someone like Star to overthrow her and making all of the Nexus a "peaceful" desert, where there's no one left except her and whatever she can summon.