Good old subtext.
https://dynasty-scans.com/chapters/she_gets_girls_everyday_ch02#18
Which makes me wonder about today's use of the term "subtext".
To borrow from wiki: "Subtext or undertone is any content of a creative work which is not announced explicitly by the characters or author, but is implicit or becomes something understood by the observer of the work as the production unfolds. Subtext can also refer to the thoughts and motives of the characters which are only covered in an aside. Subtext can also be used to imply controversial subjects without specifically alienating people from the fiction, often through use of metaphor."
...*looks at title of story* ... Uhm... I think, this is actually text. Nothing between the lines, even if she didn't finish the sentence properly, between Iku's possessiveness of Kyouko and her dokidoki-reaction to Kasumi, it's pretty much out there.