Idol group Hatenkō Heroism (破天荒ヒロイズム) doing a performance marking the 30th birthday of the red member (who is also producer).
The theme of the group is that they're a sentai team of otaku.
Kurume Maimu (red): manga otaku (hence the beret)
Aoba Rui (blue): cosplay otaku (and a prince regally holding up laminated cards)
Hitose Manaka (yellow): an idol otaku
Minokoshi Hinata (purple): a theater otaku
Nami Hinami (green): a rhythm game otaku
The first song is Tōbō Aquarium (逃亡アクアリウム), basically Runaway Aquarium.