Ryuuki Kirishima, the protagonist, wonders why his older sister Rinko hasn’t shown him her room in four years. When he finally opens the door, he discovers Rinko’s true nature, leading him to an emotional release amidst the chaos. His feelings intensify to a critical point, and the secret between them will linger into their adulthood.

Ark Academy was chosen as a model case for a school with mixed races. Aegis, an elf enrolled in the school, and her teacher came to the sea at her invitation. The dignified and beautiful features, the toned body, and the plump fruit on her chest attract the gazes of the men on the beach. […]