Three elementary school students end up going to an old mansion after hearing rumors of ghosts. They find a mysterious boy named Mayuki.

Mayuki starts attending school on his 12th birthday, but his new school life is interrupted by a bomb threat.

Minori asks Mayuki to fix her souvenir. Mayuki can’t fix it, so he and the gang venture into the restricted zone to find a replacement.

Minori and Rakuta are trapped in an elevator, so Mayuki and Kota must find the backup generator to restore power save their friends.

Mayuki and his friends decide to visit Yaya. They find that her family is being harassed because her brother Shichiro is a key witness.

Mayuki has to race against the clock to find Shichiro before the trial. How did Shichiro disappear from a moving train.