In episode six of the Watamote anime, otome game champion Tomoko Kuroki has some problems with hygiene due to prolonged gaming, then learns a bit about sex IRL with help from cats and ants. "Since I'm Not Popular, I'll Go See the Fireworks" is then capped with an interesting treat. Namely, a vocaloid cover of "Natsu Matsuri" ("Summer Festival"), originally by Jitterin' Jinn and popularly by pop punk band Whiteberry.
The original Whiteberry's take on "Natsu Matsuri"- use "Closed Captions" for English translation
thumbnail via rxjx's ever insanse Hatsune Blitzkrieg.
Meanwhile, you might have been wondering about the end of episode 5... that's a homage to the Japanese Folktales anime.