雨's manga / #death game(1)

I thought it was familiar, but it turns out I watched the anime years ago.     Why is there a “no yaoi” tag   Now that I think about it, instead of making the GF have sex with Mc's BF, he could have done it with his BF too; it's not like it specifically said have sex with a girl, but then the preparation would take too long, wouldn't it?