The childhood friends with an 8-year age difference, Aa-chan and Ryouko, are teacher and student. While Ryouko approaches Aa-chan, Aa-chan cannot take a step forward due to her position as a teacher. After receiving matching phone charms as a gift, Aa-chan buys a pair ring in return, only to realize she has lost the charm…!? The distance between the two shrinks significantly in 'STEP UP', a girl who loves Ryouko appears in 'STEP FORWARD', and tears are a must in 'step by step' featuring wedding dress × wedding dress… The love journey of Ryouko × Aa-chan is filled with moments. Additionally, 'Leave hickey?' showcases the dazzling love marks on the body of kk Kim and art teacher Miyano-sensei, along with the unpublished work 'sercret love'!