Sumire Midō serves as a miko alongside her younger sister, Ran Midou. The sisters dedicate themselves to punishing women they judge for using large breasts to seduce men and wearing provocative clothing in public. They summon a giant octopus named Takochu-kun to carry out these assaults, frequently targeting Minori Sumitomo. Ran conceived their collective title, the "A-cup Idol Miko Sisters," which Sumire dislikes, reflecting her deep resentment toward busty women.

Their actions include intervening immediately when they encounter Minori attempting to comfort a lost child while in a revealing costume, summoning the octopus to assault her as punishment for perceived indecency. This pattern repeats, with the sisters indiscriminately deploying Takochu-kun against women they deem inappropriately dressed throughout their appearances.