[spicytuna]

Japanese girls in general are pretty hard to read because they'll hardly say anything negative. They'll always be ladylike in front of you and will always find a way to avoid the word, "no".

For someone who isn't used to them, it can be easy to mistake tataemae with affection.

Sending her off with a letter will give her the opportunity to respond with something vague like, "I'm very happy that you feel that way" or "I hope we can meet again soon". (Which in my experience are both negative responses.)

I know it's too late but you should have told her your feelings in person. Otherwise, she'll probably keep you guessing for the next 3 years.