If you liked the School Days: Valentine Days anime, the Anime-Planet community thinks you'd like:
Yukino and Kanade are twin sisters who now share a room at their new school in Tokyo. Ever since they were little, the pair has been exceptionally close – perhaps even a bit too close for siblings when eyes are turned away. But soon a girl named Sakuya, who often tails the two, begins to grow closer to Yukino; and after an alleged confession that she hears about, Kanade begins to get worried that something is going on behind her back. Can the three of the girls keep their relationships with each other on stable ground, or will jealousy and heartache come crashing down on them?
Both Candy Boy and Valentine Days are lighthearted, short, romance based specials, and, with little plot (though definitely a lot more in Candy Boy) to speak of, provide little purpose other than a quick, cute, and amusing watch. Though Candy Boy has more substance, and Valentine Days makes less sense without School Days, check out one if you liked the other.