Technology (I) (技術) is the 15th chapter of the manga series.
Chito asked Ishii to help her fix the Kettenkrad. Ishii agreed but in-exchange, Ishii wanted the girls to help her with her plane building, which is located under an old air base under the ground. The plane Ishii makes is also completely original with a mix of old and modern planes design. Though some more advancde planesares impossible for them to understand, said by Ishii.