When the popular online game Yggdrasil is shut down, a lonely player named Momonga decides to stay logged in and take over this digital frontier.

"One day, a girl who loves me will suddenly appear before me"—Middle school teacher Nobunaga has always been dreaming of such a gal game-like situation. However, the one who appeared before him was Kichou, a 14-year-old girl who proclaims herself as his wife. Appears to have arrived from the Sengoku era, she mistakes Nobunaga as Nobunaga Oda and urges him to conceive a child with her. Thus begins the age-difference love comedy between a gal game-loving teacher and a Sengoku era expert princess.

Founded in the Taisho era, the "Red Flower Opera Company" attracts people's hearts across generations on a beautiful and gorgeous stage created only by unmarried women. The 100th generation students who have passed through a high magnification and entered the "Red Flower Opera Music School" to develop the human resources. Sarasa Watanabe, an innocent girl with a height of 178 cm who longs for "Oscar-sama." Ai Narada, a former national idol who is indifferent to everything, both dreams and friends. The music school life full of hope and conflict, where everything is disjointed, is about to begin! (Source: MAL News)

Izayoi, Asuka, and You have been invited to participate in a Gift-Game at a hot spring village to help the small community there find a new water source. OVA bundled with the eighth volume of the light novel.