There's already a warning on chapter 1 about force sex, so I don't know why you guys are angry about the manga not having r@pe tag when you are already warned before you start reading it...
Yea, and as sad it may sound, this is a generic plot driver in most Japanese Yaoi stories.
If they want to, they could just drop the story when they feel uncomfortable.
Or they could just continue reading their soft and wholesome KR BL.
Like honestly remember that these two different industries have two different writing styles. If you are more wholesome, try to expect your tastes to be more along shounen-ai or KR Yaoi. JP Yaoi is more likely to harbor more mature and dangerous content since the expected audience are more mature and less impressionable audiences.
If you're reading this and got mad about the r@pe scene you did this to yourself, before even starting with chapter 1 the uploader already gave a warning about forced sex so you should know about it and have time to back out and decide to not read it. You guys are just being dramatic...
(Just because I read this doesn't mean I condone this actions, I'm simply intrigued)