Childhood Friend Romance: At the beginning of the game it's revealed that he actually confessed to Ran once and got turned down.
Lovable Sex Maniac: Junichiro is first introduced fondling an assistant. That's just the tip of the iceberg.
Oblivious to Love: Averted. Junichiro acknowledges pretty early on that he knows how Yukino feels but simply doesn't feel like a relationship upgrade. On the other hand, the girls seem to think he doesn't know.
Only Sane Man: Junichiro is literally the only sane man in that he's the only man on Earth to remember what things were like before the aliens brainwashed everybody. Putina on the other hand is the only sane woman by this standard.
Porn Stash: Jun's is discovered, but he manages to turn it around by convincing the girls that theyre Covert Perverts and no better. The porn is just confiscated instead.
Betty and Veronica: The sweet ditzy childhood friend Yukino and the extremely famous, beautiful, tsundere badass Putina respectively
Childhood Friend Romance: She comes to Junichiro's house to wake him up in the morning, voluntarily does his household chores, cooks for him (albeit badly), and is otherwise totally devoted to him. Even though she's the president of Japan.
Clingy Jealous Girl: The only thing that can make Yukino really angry is somebody taking Junichiro away from her. At one point she bans exports of Junichiro to prevent Putina from taking him to Russia. To her credit she doesn't interrupt any truly intimate moments between Junichiro and Putina even when she's right there, and still maintains a friendship with her love rival.
Covert Pervert: Yukino plays more eroge than Jun. Also, shes freakishly good at kissing because she made sure to practice tying cherry stems with her tongue.
Dogged Nice Guy: Yukino moves into Jun's house to try to make him dump Irina and pick her. Well, that's probably the more unpleasant side of the trope. At least she doesn't do any sabotage more direct than interrupting their intimacy.
Feminine Women Can Cook: Yukino's pretty set on cooking for Junichiro so she can compete with Ran and Putina, even if she does ruefully acknowledge her status as a Lethal Chef.
Forceful Kiss: Yukino kisses Jun in front of Irina to prove that she's serious about winning him away from her. She's really good at it.
Took a Level in Jerkass: Yukino actually invades Jun's home and won't let him and Irina be alone at all for the beginning of Irina's afterstory, but in the end it's just because she doesn't remember Irina. When they become friends again she mellows out and tries to step aside.
Graceful Loser: Irina, when Junichiro tells her in Yukino's route that he won't be going with her to Russia because he's in love with Yukino. She's disappointed, of course, but she also pushes him to confess to Yukino as quickly as possible and she thanks him for being her first love, whilst expressing the wish to remain friends.
Supreme Chef: Irina learns from Ran and eventually becomes very good herself, though not up to Ran's level yet.
Tsundere: Though she doesn't know what the word means when it's lampshaded. Oddly enough she DOES know what it is in Yukino's route.