You can find them on comicpark. Link in other comments. The yandere guy isn’t introduced in those, what you see on this website is all of him in the story so far. The missing chapters is basically just
Spoiler?? Yuuma getting hurt for a bit while rescuing Shuumei, and Shuumei telling Yuuma that he sees Yuuma as an important friend (and Yuuma going wtf that makes no sense)
You can find them on comicpark. Link in other comments. The yandere guy isn’t introduced in those, what you see on this website is all of him in the story so far. The missing chapters is basically just
Spoiler??
Yuuma getting hurt for a bit while rescuing Shuumei, and Shuumei telling Yuuma that he sees Yuuma as an important friend (and Yuuma going wtf that makes no sense)