Complex sentence: As time passes, Natsuo finds out Yuna is actually Masashi; however, because of her love towards him, she keeps his identity a secret and helps Masashi out in numerous situations, hoping to win his love.
Split into simpler sentences: As time passes, Natsuo finds out Yuna is actually Masashi. However, because of her love towards him, she keeps his identity a secret and helps Masashi out in numerous situations, hoping to win his love.