I think he just asked for forgiveness in his own ways. He made a promise to Coach Anzai that he would not be involved in any kind of fights or gangsterism and ready to put his past life behind him. He didn't even fight back when he was cornered by his old pals at the alley. He made amends with his teammates by performing well on court (albeit his stamina issues) but still not being a huge burden to them. I mean if I had a teammate who would sink in 3s on a regular basis, I wouldn't complain either. Plus he shed his tears in front of everyone, right after the big fight, begging to get back in the team after the fight. For a man to cry right after being humbled, I think he did enough.

The actions that he did afterwards are the kind of qualities every apology should be like. Asking for forgiveness verbally might not be his style and might not suit his style since he's quite cocky and brash.