YURI!
He's the year above but thinks because he's the oldest street kid (years as a statue guarantees it) that he needs to 'look out' for the other orphans, waifes and strays - and he had the good luck of being taken in by Mr Mondragon.

He's worked hard on his education to improve so he'd be down to tutor/help. Probably not doing it for him but would definitely help walk him through it.