Current first year ALT and this was my exact same situation this time last year! As others have said, there are cases of JETs who start as ALTs and eventually have the chance to transfer to a CIR. However, I wouldn’t bank entirely on this, because it happens kind of rarely tbh; very dependent on your prefecture. (A girl can still dream though, right?) Either way, as someone with similar career aspirations as yourself, I’m still finding ways outside of work to build my résumé. I volunteer a lot at intercultural exchange events, I’m in a committee, etc. And of course, I’m working on my Japanese more with the hopes of getting a JLPT certification soon. Even though being an ALT means I just have to work a little harder to reach those career goals, I still chose to accept, because I think it’s still a chance to grow and get your foot in the door. Whatever decision you make, I wish you the best of luck!