Ya-gan-bi-haeng (2014) Night Flight

Three teenage boys Yong-ju, Gi-Woong and Gi-Taek, were once best friends in middle school, but they become estranged from each other once they enter high school. While Yong-ju and Gi-Taek still remain close, Gi-Woong becomes a jjang (Korean slang term meaning "best"), one of the strongest fighters in the school, and begins to hang out with Seong-jin's gang (Seong-jin's parents are powerful figures, making him a bigwig among his schoolmates). Yong-ju becomes concerned when he finds out that Seong-jin's gang is mercilessly bullying Gi-Taek, an eccentric manhwa fan. Under intense pressure to get into a prestigious university because of his financially struggling single mother, Yong-ju develops an unlikely relationship with Gi-Woong, who tries to break away from Seong-jin. But when Gi-Taek learns that Yong-ju is gay, he betrays his friend and joins Seong-jin's gang in ostracizing him, telling them that Yong-ju has loved Gi-Woong for years.