What happened to Jin?

[Where's Jin?]

Number 1, I don't know if this silly website made my username "Mariasisla" or "Where's Jin", my stuff glitched.

But anyway, as the subject says, what happened to Jin? He is shown in the web comics and digital media but nowhere in the game, from what I've seen? Like Sakura is there; she even has a voice line about Jin so where is he? Is he not one of the main characters like in the comic stories? He is literally on the cover of "chapter" one and in some of the in-game art. I know this is a silly question but it is a little confusing because you'd think the other main character in the story would be a partner you summon like his partner, Sakura but I guess not? Does anyone know what happened to him in-game? Like did he die or something? Cuz even in Sakura's voice line, she is lost on where he went lol