Translated transcript follows, courtesy of Bill Gordon.
Recommended reading: A Glorious Way to Die: The Kamikaze Mission of the Battleship Yamato.

Transcript
Dear Masanori and Kiyoko,
Even though you can't see me, I'll always be watching you. When you grow up, follow the path you like and become a fine Japanese man and woman. Do not envy the fathers of others. Your father will become a god and watch you two closely. Both of you, study hard and help out your mother with work. I can't be your horse to ride, but you two be good friends. I am a cheerful person who flew a large bomber and finished off all the enemy. Please be an unbeatable person like your father and avenge my death.
From Father