From Chibi Manga:
This time i will say it honestly—there is only you. the person that i don't want to see the most in this world—"my ex-boyfriend"

During junior high school, Mitsu had her first boyfriend and first heartbreak. Without really resolving the problems between them, she is now a university student. This year, she definitely wants to have a new love, but unfortunately her ex-boyfriend Kaede is her neighbor! Five years have passed and now he is a popular guy, but his smile didn't change a bit. ...Gosh, love will bloom again... He knows all her weaknesses, she wanted to know about his previous girlfriends, and he led her to misunderstand by his kindness. Her ex-boyfriend is so troublesome!!!

But the thought of 'if we didn't break up that time' is unstoppable. Is a 'retry' with an ex-boyfriend okay!?