Theory 1:
Chi posses/takes control/takes over all the bodies in this town, especially people around Ryota and uses them like a surveillance system to constantly keep a track of Ryota - that's why even tho Hayato was a huge pain in his ass, he didn't permanently get rid of him, but possessed him to use him and wiped his memory to make things easier for him
Also based on this I have to imagine there's limits to how much memories he can wipe of his victims
Cause if he could he could've wiped Hatano's entire existence from Ryota's memory and likewise but HE DIDNT.
Theory 2:
Chi uses these bodies in a parasitic relationship using them as nutrients/spare fodder to keep him well powered, especially when significant damage to his main body
Theory 3:
Since the girl who likes Ryota got possessed when she was younger - around the same age as when Ryota said bye to chi - chi either went on a rampage/started planning how to get back into Ryota's life - took action for all the things he'd need for survival + get Ryota back
These theories combined would also make sense why he took over and swallowed the girl and her family - cause it would be the only thing that makes sense
Also, I NEED TO KNOW HOW TO END THAT KID BRUH TF
Coming back after 4 years and fuck its so refreshing to see all the hate this manga getting ლ(´ڡ`ლ)
back in those days ppl glazed this manga and hated anyone who offered criticisms, like yo,the mc and love interest and side characters ARE TERRIBLE PEOPLE, miscommunication trope is overused, whole love story is based on baby trapping, non-con, controlling abusive tendencies and stockholm syndrome and WORST PART the narrative tries to portray all of that shit as "healthy loving couple with ups and downs like all love stories" LIKE NO???? fuckin HATED this manga
damn i was aware of the other parts of the toxicity in their relationship but i didn’t even think abt the stockholm syndrome part but now that you bring that up, that makes SO MUCH SENSE