Kokou no Hito

On his first day of transferring to a new high school, a loner named Mori Buntarou is cajoled by a classmate into climbing the school building. Despite knowing that one misstep could send him spiraling to his death, he moves forward, and upon finally reaching the top, Mori experiences a sense of fulfillment. That feeling, which seems to be telling him "You're alive!", gives birth to a passion for rock-climbing.

Note: Sakamoto Shinichi did both the story and the art from Volume 4 onwards.