Replying...
Intro. In order to save the life of her sister, Haruka (10 years old), from end-stage cancer, a radical surgery to remove consciousness was performed. The innocent and cheerful Haruka agrees to transfer to the body of the only available donor: her own grandmother, Akiko (45 years old). The operation was successful, transforming the frail boy into a beautiful mature woman with tanned skin and an extreme hourglass body, including massive Z-cup-sized breasts. Even though she is now a very plump and prominent woman, Haruka still maintains her innocent personality and is determined to live her new life without pain while taking care of her family.

"My 10 Year Old Little Brother Who is Now My Chubby Grandmother"

@Akira