If Her Flag Breaks

On her way to school, Nanami Knight Braidfield encounters a boy who saves people from a collision.

Souta Hatate meets his old friend Okiku. They have renovated the Quest Dorm thanks to Mimori Seiteikouji's volunteers.

Everyone is settling in at Quest Dorm when Akane gets a female android named Ninjabayashi Ruri from her family.

The week-long track meet starts. A new member joins, and everyone tries to prevent the Quest Dorm from shutting down and Souta being expelled.

Souta promises to go on a date with Akane, and the rest of Quest Dorm finds out about it, and wants to go as well.

Daimyouzamurai Mei, a transfer student, joins class 1-F. She seems to also have the ability to see and manipulate flags.

Hatagaya Academy goes on a trip near the ocean, and Souta meets Daishikyougawa Kurumiko there.

Souta returns home with Kikuno during summer break, and is spoiled by her. Ruri shows up all of a sudden and takes him away.

The Quest Dorm goes to Nanami's home country, the Principality of Bladefield, and meets Nanami's little sister Hakua, and the crown prince.

The mysterious girl is idol Serika Ginyuuin. During her concert Souta's powers increase and time freezes.

Souta fights the Angelus Gemini to protect his world by placing 'Death Flag' on his enemies. Nanami learns from Riru how she is linked to Souta.

Souta regains his memory and learns he knew the girls once before, but had Laplace's Demon save them. Souta and the girls fight the Premium Ambriel.