IMHO, that was practically a forced/rape scenario; the only things that redeemed it in my eyes are: (1) "Hey Mikey. I Think She Likes It", and (2) ... "BUT IT'S AZUMA TESSHIN!"
Clearly in a vanilla-themed hentai, "Chivalry Ain't Dead" And by the close, certified jerk-ass Katsuragi sheds tears of blood as he sobs aloud (probably with other males): "Nasu, you Lucky Bastard!"
For me, THIS was the story that cemented the notion among h-fans of referring to Homunculus as (in my own words) "the Most High Lord of Vanilla-flavored Hentai"
Many moons ago B.L. (Before going Legit), there was a h-manga story posted on FAKKU where the female protagonist declared to her father: "I'm Gonna Be A Bride." (some others might remember the story and artist). And just like before (its previously censored version) on Page 18, the baby is (probably) thinking: "I'm Gonna Get A Daddy." And the (some others call it) "happy sex with love" combo was just as magnificent now, as it was then.
(1) Might this be a case of "reverse" harem {one female, many males}, and (2) did her "switch get flipped" so that on returning to school, she offered her classmate a chance to {ahem} see something?
In the terminology of many a pinball game, Haru-san's life got (ahem) upgraded as follows: Page 2 - "JACKPOT!" Page 7 - "SUPER JACKPOT!". Page 18 - "SPECIAL" (usually results in an extra ball or a reply, depending on the game).