Narumi & The 20-Year-Old Yu

Narumi & The 20-Year-Old Yū is the twenty-fifth chapter of the Owari no Seraph manga.

Short Summary
Yū meets Sergeant Makoto Narumi and his squad. Shinoa and Makoto Narumi's squads will work together on this extermination mission. Attempting to one-up the 19-year-old Narumi, Yū says he is 20 years old, despite being only 16.

Yū is summoned for his punishment. Once in private, Guren informs him that he is there to punish Shinoa. Goshi makes an embarrassing illusion of Yū screaming for help and forgiveness. Shinoa's squad runs in, and Guren lectures Shinoa.

Guren challenges Shinoa to a three versus five battle: Guren, Mito Jujo, and Shinya Hiragi against her entire squad. If Shinoa loses, her entire squad will be held responsible and punished. He gives them ten seconds to prepare. Shinoa and Mitsuba describe the abilities of their demons, and the battle begins.

Long Summary
Yū wanders around the Ebina rest stop. He chats with Yoichi and Kimizuki until Sergeant Makoto Narumi and his squad arrives. The two squads are paired together for this mission. Narumi says he does not trust a bratty kid who showed up late to his first meeting. Yū asks Narumi his age, and he answers nineteen. In response, Yū says he is twenty with a baby face.

The girls return from the bathroom, and Kimizuki tells them they were in there for four years because they are all now twenty years old.

Second Lieutenant Shigure Yukimi summons Yū for his punishment, and Shinoa and Mitsuba attempt to take responsibility for the squad's tardiness. Yū meets with Guren's squad. Guren is already aware that he is covering for his friends, and he appreciates Yū's development from being so focused on revenge to being loyal to his new family. Shinya and Goshi tease Guren, and Yū asks them if Guren considers his squad family. Mito Jujo tells him they have been partnered with Guren since they were 15 years old, which was one year before the apocalypse began. They survived the virus when they were 16 by receiving the vaccine.

Guren tells Yū is there to punish Shinoa. Goshi begins a humiliating illusion of a bound and naked Yū with four tiles piled on his thighs. Goshi makes the illusion Yū cry for forgiveness, help, and his mommy, screaming that he peed his pants.

Shinoa's squad rushes in, and Shinoa quickly orders Shikama Dōji to destroy that illusion.

Guren lectures Shinoa, scolding her that a little mistake could cost her family and squad their lives. He challenges her to a test: Guren, Mito Jūjō, and Shinya Hiragi in a fight against her entire squad. He gives her ten seconds to prepare.

Shinoa explains that her ability is to detect anything within the attack radius of her scythe. Mitsuba says she can spawn multiple demons for an attack, but they are essentially only good as decoys. Shinoa assigns Yoichi to keep Shinya at bay while she and Mitsuba fight Mito Jūjō, and Yū and Kimizuki will keep Guren busy. She orders the squad to stay within the radius of her scythe. Kimizuki and Yū do not have time to explain their abilities.

Narumi looks forward to the rookie hazing as the match begins.

Shinya fires Byakkomaru, surprising Yoichi when the materialized tiger appears at them from behind. Jūjō punches through Mitsuba's demon spawn. Yū and Guren clash.