Souta Ahara-ya, living in Okinawa, is an elementary school student who is not good at socializing. Learning that a public hall will be built on the vacant lot where he used to play Catch Ball with his brother, the only person he opens his heart to, he tries to start a one-man anti-construction movement. That's when he meets the free-spirited Architect, Reiko Tetsumura... Awakened to the fascination of "Architecture" by her, the boy embraces the dream of becoming an architect and enters the department of architecture at a prestigious University in Tokyo, but――.