You are so right — my grandmother started learning Portuguese when she was 27 (already fully grown and with tons of information in her brain), and she mastered it really quickly. And I’m sure she’d have done so had she been 87 with the effort she made! Japanese must be really hard, especially the alphabet(s)! My sister tried to learn it but she gave up! It must be quite a feeling to master it and to be able to read it, though! Do you want to keep learning it?