Honda's sister is an unseen character in the Yu-Gi-Oh! manga. She is the sister of Hiroto Honda and mother of Johji.
Honda was forced by his sister to babysit her son, Johji, the day Honda brought him to Kaiba Land.
When Honda collected Shizuka Kawai from Yonezato Hospital, he was not sure if she had a change of clothes, so he brought some of his sister's hand-me-downs, which included a biker-style jacket. He said he was not sure if they would look good on Shizuka, as he thought they were kind of loud.