Bunny Drop, Vol. 1 by Yumi Unita

In this heartwarming tale, a 30-year-old bachelor named Daikichi Kawachi finds his life turned upside down when he attends his grandfather's funeral and discovers a mysterious young girl named Rin. To everyone's surprise, Rin is revealed to be the grandfather's illegitimate daughter, leaving her with no one to care for her. Despite his lack of experience and the challenges of single parenthood, Daikichi makes the bold decision to take Rin in, embarking on a journey of growth, understanding, and unexpected familial bonds. As they navigate their new life together, both Daikichi and Rin learn valuable lessons about love, responsibility, and the true meaning of family.