How can I wirte something in japanes and send it to the arduino? I wanted to send it to a lcd.
you must implement a Japanese font to do so.
Maybe there are LCD's for the Japanese market that have them build in, but I am not aware of that.
I believe some LCDs have japanese character built in. Apparently this one does. Basic 16x2 Character LCD - White on Black 3.3V - LCD-09052 - SparkFun Electronics