OBA-143 I want to tie up my mother! Ryoko Iori

Sudden news of a death... Having lost her beloved husband to illness, Ryoko was left with a huge hole in her heart and was living a listless life every day. Her only son, Kenji, could not bear to see Ryoko like that and wanted to somehow cheer her up. One day, Kenji found a scroll among his father's belongings. Kenji devoured the scroll, which was titled "The Book of Bondage Five Rings." And then Kenji learned something: his mother, Ryoko, had an extraordinary interest in "bondage."