Can I change my birthday?

Yes, from Settings → Birthday → Change your birthday, once every 3 hours and only a few times in all. Right after you first enter your birthday, you have 30 minutes to fix a mistake without using up a change. If a change raises your age, it takes effect after 3 hours. If Google Play says the account belongs to someone under 18, the birthday cannot make it 18 or older, and if a parent set your age, only your parent can change it. If your birthday is wrong and you have used every change, email admin@dochiai.com.