"The Music of the Sea…"
Izuku's lips part slightly.
"I…."
"For a moment, Kacchan…"
Izuku furrows his brow, redirecting his gaze to the seafloor.
"I think I heard it."
Katsuki smirks, and the blond delicately brushes his tail against Izuku's as he swims away.
"You haven't heard nothing yet, Izuku."