  We investigate the twisted bilayer graphene by a two-orbital Hubbard model on
the honeycomb lattice. The model is studied near 1/4 band filling by using the
singular-mode functional renormalization group theory. Spin-triplet $f$-wave
pairing is found from weak to moderate coupling limit of the local
interactions, and is associated with the Hund's rule coupling and
incommensurate spin fluctuations at moderate momenta.
