After The Graduation Ceremony...a Gift From My Mother-in-law To You As An Adult-. Rei Kimura

Yuu lives in a dormitory at a private school away from home. Her fulfilling student life is coming to an end, and graduation day has finally arrived. Her parents couldn't come due to work, and she thought the day would end alone, but from across the street, running towards her with a smile, was her stepmother, Reii. On the night they enjoyed a graduation celebration just the two of them—her secret crush—Yuu escorted Reii to her hotel, where she gently kissed him, saying, 'This is my graduation gift for you...' And so, he climbed another step on the ladder to adulthood.