[sae is Rin's older brother and Rin is sae's young brother]

Even though they are sisters, Sae has more feelings for Rin, Sae really loves Rin like she's obsessed

Today Sae and Rin are in the men's changing room (school) they were just the two of them, until I saw Rin's smooth body, her white, well-groomed skin, her white thighs, her tempting stomach.

sae felt tempted and approached Rin and whispered

Sae: Rin...Your body is really tempting...