>>21592
Fine, but fair warning: Both the middle and end will be spoilered so you can properly understand why this is shit.
If you don't want the middle spoilered, jump straight to the end of the first spoilered paragraph. The second paragraph will be a TL;DR.
MC finds out that Stacy has been stealing other's boyfriends left and right and fucking every guy in sight after he catches her about to hook up with some guy after they kissed (IIRC), while it is hinted strongly at Stacy doing it because she knows there won't be consequences as she has a brain tumor and will live in another country after a few months so it can get operated (and she knows it's unlikely to kill her), which is the reason she's doing all this shit. MC then proceeds to tell her to stop and after some drama she does (he does not know about the operation)
After a while of being together, she goes to goes to a different country, it works but she loses her memories and spends the next 7 years living with her creepy siscon of a stepbrother telling her about her life to help recover memories. Eventually they visit back in Japan where MC was waiting for her for 7 years, after a while Stacy recovers some memories, remembering MC last of all her friend group, telling him she didn't actually love him back then but now it's totally different.
TL;DR: Fucking sociopath fucks with everyone, likely gets fucked with by her brother because sociopathy runs in the family, then gets a happy end that's definitely not her getting MC's sweet sararyaman bux