The story is that the basketball club has a strict hierarchy and the juniors have to do whatever the seniors say. So, the senior here tells the junior to come with him, then takes him to a quiet room of the gym, tells him to change into the skirt (which he got from his sister), and get down to "serving" him. The junior is reluctant at first, but does as he's told because the senior's orders must be followed without question. He's reluctant to suck a dick, but he goes with it. Then he's really nervous about anal, but he starts to enjoy it. He cums and he gets a feeling of elation that he compares to when he scored a goal in a basketball game. By the end, he's totally converted into being his senior's cum dump.
The writing is good but the dialogue is really slangy and may be hard to translate.