18+ Itoshii Kanojo no Mamorikata

Yuuto enrolled in a military school in order to fulfill a childhood promise with Yui. But when he met her again, she demanded to know why he came there. He realized that her smile had disappeared. This is because their class is ridiculed for being weaker than other classes. Their classroom is not well furnished and his bed is more like a table. Their teacher announces that there will be a battle in which the rewards will be a proper desk and chairs… and an air conditioner as well! Yuuto decides to help their class win this battle and bring a smile back to Yui’s face.

(Source: Hau~ Omochikaeri!)