Evenicle

A 2015 H-game by Alicesoft, Evenicle is about a guy who desperately wants to get laid with twins.

Asterisk is an orphan boy who grew up in a small island with a bunch of old people and his two twins stepsisters. He is desperately in love with them and so are they are with him, but laws determine that in his world, unless you're a knight, you can't have vaginal sex out of marriage, and only knights can have more than one wife. That isn't just a human law: the mother goddess Eve will punish the transgressors by giving them a black ring which will curse them and mark them as outcasts by the rest of their lives.

Not wanting for himself and the twins to become like this but unable to choose just one, Aster decides to leave his island by swimming in order of becoming a knight by the proper means in the nearest continent. He almost drowns but is saved by a mysterious blonde girl called Corpis that soon leaves after giving him CPR. Soon after, he meets a knight called Ramius who finds him suspicious and demands he proves he isn't an outlaw by hunting monsters and getting money of it, something outlaws can't do.

Aster proves himself worthy but before he can make any progress on his quest to be a knight, a girl who lives nearby, called Colpis, is kidnapped by a group of outlaws. Needing a helping hand, Ramius reluctantly promotes Aster from civilian to soldier so he can fight, since another of Mother Eve's laws is that normal humans can't kill each other. She however grows angry with Aster because of his perverted behaviour and goes alone. Aster decides to follow after her anyway.

In terms of gameplay, Evenicle is a turn-based JRPG with a first-person view, but the on-field model of characters are 3D. The encounters with monsters aren't random but predictable: a meter fills up the screen the more you walk, with its speed changing in accord with your character's levels and the levels of monsters. Aside of storyline bosses, you also meet optional bosses whose models are visible on the field. You also have to manage Battle Points, a resource that is accumulated at the rate of one per battle turn and is consumed by using "Skills", techniques each character has with a multitude of effects.

Directed by Youichirou. Mangagamer released an English version in 2018.

Tropes used in Evenicle include:

Always Identical Twins: Kyou and Kinou are pretty much identical bar the fact Kinou has shorter hair.
Attack of the 50-Foot Whatever: Some bosses are giant animals, like a giant lizard and crab.
Bare Your Midriff: It's a Dreissen family trait: both Ramus and Achieval walk around with their belly buttons exposed.
Big Freaking Sword: Yarase walks around with what is pretty much a Buster Sword on his back.
Chivalrous Pervert: Aster is very perverted but also very courteous towards the ladies.
Composite Character: Pancho Quixote is a composite of the two main characters of Don Quixote: he has Sancho's body type (rotund), but Alonso's chivalry.
Conveniently Orphaned: Aster had no parents to dissuade him of his crazy plan to become a knight.
Eyepatch of Power: Rocherfort wears an eyepatch on his left eye and is also the Prime Minister of the Kingdom of Eden.
Foreshadowing: Aster assess that the Black Night is strong as the White Knight. Asteval also says he is powerful as the White Knight. Asteval of course, turns out to be the Black Knight.
Gonk: Queenbelle looks pretty different from everybody else on the cast. It also doesn't help she is morbidly obese.
Happily Married: Once they become married, Aster and Ramius became a pretty loving couple. One may say almost sickening, that even Ramius becomes self-aware about it and dislikes it.
His Name Is--: Riche and the party are just about to discover why a member of Snake Crest thinks war on their world don't would be such a bad thing until he gets mortally stabbed by a black knight, also a member of Snake Crest, that thinks his ranting is useless. This seems more of a coincidence though.
Loophole Abuse: A lot of plot points revolve around how people deal around Mother Eve's rules, especially efforts by the antagonists to circumvent them.
Meganekko: Colpis is pretty much a textbook example of this, being a timid girl who wears glasses.
Not So Different: When Aster meets the Outlaws after they rape Colpis, they argue he is pretty much like them by pointing how much aroused he was by her rape. The game actually gives you an option to agree with them or not.
Stripperific: Mertel, the queen of the Kalar, wears a dress which exposes almost all of her breasts and barely covers her vaginal cleft.
Theiss Titillation Theory: Mertel is basically one small breeze and one small slip away of exposing both her vagina and nipples.
Thou Shalt Not Kill: Enforced by Mother Eve's rules. Killing someone without being a soldier makes you an outlaw.
Tomboy: Despite her very flattering outfit, Ramius' behaviour is overly masculine, what causes her serious trouble in finding a partner. Discovering Aster loves her despite of this makes feel her pretty happy.
Underboobs: Ramius's clothes don't cover the underside of her breasts.
Walking Shirtless Scene: Achieval, Ramius' brother, is always walking around with a open shirt showing his well-defined abs.
War Is Hell:
- The world of Evenicle never actually went through war thanks to Mother Eve's rules regarding killing, with the Outlaws being too small of a faction to present any danger. However, fictional books have speculated over it, and the conclusion is that it would indeed be an horrible experience.
- Snake Crest members seem to be however of a different opinion, but just when one is about to explain himself, a dark knight stabs him because he was ranting.