In the United States, at least, we do not say we’re second year high school students. Instead, we say we are sophomores in high school. This doesn’t translate well to other countries, though, so I suggested that you change the phrasing to when you began watching One Pjece instead of who you were. I also suggested summer break instead of summer vacation because a break is more general. I’m on summer break means I’m not going to school or work for a while. I’m on vacation means that I am on a specific trip.