When their friends Kadoi and Hasumoto reveal that they’ve been dating for a whole month, Oka and Sawada are more jealous that their friends have lovers than anything else. So, when the change in their friends’ relationship causes them to be more conscious of each other, they can’t help but wonder what it’d be like with each other—in more ways than one... (Source: Yen Press) Note: Includes the one-shot "Hajimari no Period"