This piece of shit deserves an 8 at least (no more than 9 tho) because IT'S COMEDY. It's not trying to teach you how to love or about life. You don't have to expect some deep development or something like that. Read it and laugh. If don't, go read Tokyo Ghoul and feel special and edgy.
I mean, the story and plot are basic/generic garbage but that's what makes this shit funny. It doesn't take itself seriously, and that's what a lot of people tend to miss reading. Also, it's Japan that we're talking about. You sound like you don't know how they are.
Yes, this shit is bad, but that's its purpose and that adds a lot, making it enjoyable
I wrote this because the last chapter almost made me laugh my ass off, and I'm afraid that it gets dropped because of the low reading or bad rate. Enjoy reading bois, and read because you like to read, not because you want to feel superior
Have a nice day <3