You can ask someone's grade level in Japanese by saying "何年生ですか" (pronounced "nan-nen-sei desu ka"), which means "What grade are you in?"
To ask what grade a friend is in Japanese, you can say "友達の学年は何年生ですか?" (Tomodachi no gakunen wa nan-nensei desu ka?). This translates to "What grade is your friend in?"
Ask them.
To ask someone's name in Japanese, you can say "お名前は何ですか?" (O-namae wa nan desu ka?). This translates to "What is your name?" in English.
Ask them for it.
Ask them, or search for them on Yahoo.
Ask them.
their birth certificate / ask them / ask their friends / ask their family
Ask first!
Ask him for it.
ask them!
Quel-age tu?
You ask them their password and type that in.