Her physical body changes are a source of both wonder and pleasure to Hikari, especially her breasts. Going from being a skinny flat-chested kid to an older and shapely girl delights Hikari no end. Under the guise of performing breast self-awareness, Hikari enjoys both the softness and the firmness of her mammary glands (Hikari really likes that term for her tiddies). However, math homework awaits, so Hikari adjusts her blouse, sits down at her desk in her bedroom, and soon loses herself in variables and constants...