This is something that some students say sometimes. This is the thing that probably bugs me the most. It means, "BECAUSE I'm Japanese, English is impossible." That's a super-literal translation but I feel that's the best way to express it here. It's really annoying for some reason. That weakness. Maybe they just really don't care and maybe that's fine but it's hard for me to hear it. Also, you have to think about the other students that ARE actually learning English. They're Japanese too but are somehow magically learning English.
I suppose middle school children say things that don't make sense sometimes.