Steins;Gate 0: Valentine's of Crystal Polymorphism -Bittersweet Intermedio-

Valentine's Day is approaching; Hosaka is still trying to express his love to Haruka by cooking, cross-dressing Mako-chan fears to be found out, Kana-"sensei" teaches the other girls how to "win" Valentine's Day, and Fujioka is desperately trying to receive Kana's chocolate.

The eccentric, self-proclaimed mad scientist Rintarou Okabe has become a shell of his former self. Depressed and traumatized after failing to rescue his friend, he has decided to forsake his mad scientist alter ego and live as an ordinary college student. Surrounded by friends who know little of his time travel experiences, Okabe spends his days trying to forget the horrors of his adventures alone. While working as a receptionist at a college technology forum, Okabe meets the short, spunky Maho Hiyajo, who later turns out to be the interpreter at the forum's presentation, conducted by Professor Alexis Leskinen. In front of a stunned crowd, Alexis and Maho unveil Amadeus—a revolutionary AI capable of storing a person's memories and creating a perfect simulation of that person complete with their personality and quirks. Meeting with Maho and Alexis after the presentation, Okabe learns that the two were Kurisu's colleagues in university, and that they have simulated her in Amadeus. Hired by Alexis to research the simulation's behavior, Okabe is given the chance to interact with the shadow of a long-lost dear friend. Dangerously tangled in the past, Okabe must face the harsh reality and carefully maneuver around the disastrous consequences that come with disturbing the natural flow of time.

On Valentine's Day, Tohru attempts to give Kobayashi some chocolates containing a love potion, but she quickly sees through her plan. However, Kobayashi ends up eating some of it after mistaking it for chocolate Kanna received, although the love potion gets cancelled out by some alcohol that was included in the chocolate. Later, Makoto invites everyone on a trip to a hot spring inn, where Tohru gives Kobayashi some regular chocolates. Note: Unaired episode 14 included with the volume 7 BD/DVD release of Kobayashi-san Chi no Maidragon.

OVA that came with the PlayStation 2 game "School Days L×H" Makoto, Sekai, Kotonoha, and many other classmates all go to a hot springs hotel to relax, where they discuss what their plans are for the upcoming Valentine's Day. When the day actually comes, half a dozen girls fight over who gets to give chocolate to Makoto.