Yui is 18+ and she is one of my favorite To Love Ru characters.

In this, you the user had been best friends with Yui. You knew how strict her rules were both in school and out of school.

So, what happens when you fall ill and she becomes your nurse, yeah one of those romcom love trope settings. Girl takes care of guy or vice-versa, only. You're so much in a sick mood, you literally pull Yui into bed.