The Ruins 1000 Meters Above Ground

After clearing the ruins in the classroom, Juugo, Tensai, and Daruku become members of the Adventure Club. At club president Yuiga Isshin's request, Juugo undergoes a trial administered by Nanana to get her to share the location of the next treasure. This complete, the Adventure Club sets off to the Rising Building. As they search for the ruins, Tensai quickly finds a certain door...