Heihachi Okura is a devoted player of the mobile game Girls Corps, known for spending large amounts of money on its gacha mechanics to acquire rare characters. One day, he successfully pulls an ultra-rare item described as an invitation to another world. Skeptical but curious, he is suddenly summoned from his ordinary life into a fantasy realm, where he is immediately attacked by a monster. With no other options and his life in danger, Heihachi instinctively does what he knows best: he rolls the gacha on his phone, which for some reason still functions in this new world. To his astonishment, a unit materializes from the screen before his eyes.

The girl who appears is Norl Fanya, a skilled and cheerful knight who always wears a helmet to hide her face. She is a UR rarity character, one of the best in the game in terms of performance. Grateful to Heihachi as her first master, Norl becomes his loyal companion and protector. Together, they complete a tutorial-like battle scenario, after which Heihachi vows to use his phone’s gacha system to build the strongest possible team of beautiful and powerful girls to survive and explore this new world.

The story follows Heihachi on his quest to collect what the series calls OP UR QTs (Overpowered Ultra Rare Cuties). His smartphone becomes his primary tool, recharging through the magical essence of the world and featuring apps like a map, a status viewer, and a transceiver. As he travels, he summons additional characters, including Estelle, a red-haired and highly skilled magician who is also an UR girl. Estelle has a little-sister-like personality and becomes deeply attached to Heihachi, calling him onii-san. The narrative balances action and adventure with humor, particularly through parodies of gacha game tropes and Heihachi's compulsive gambling habits. The tone is light-hearted and focuses on building a harem-style party of cute but fierce warriors.

Notable narrative arcs include the initial tutorial and survival phase where Heihachi learns the mechanics of summoning in the real world, the introduction of each new party member with their own distinct personality and abilities, and the ongoing challenges of battling monsters and navigating the politics of the fantasy realm. The overarching goal is Heihachi’s self-imposed mission to collect rare and powerful girls, a drive fueled by his past addiction to mobile gaming. The series was originally a web novel before being published as a nine-volume light novel, and it has also been adapted into an ongoing manga. An anime adaptation has been announced.