At the third Sharjah Animation Conference, at the Expo Centre Sharjah in the United Arab Emirates, Hiromi Matsuhita and his wife Kazuko Tadano mentioned when hired to do character designs for Yu-Gi-Oh! SEVENS and Yu-Gi-Oh! GO RUSH!!, that Kazuki Takahashi himself requested the character designs be simplified and aged aged down, aesthetics in general be much less dark and card mechanics be streamlined to make the franchise appealing to elementary school age children.

A major item of prior experience for the couple is the Pretty Guardian Sailor Moon anime in the 90s and Mrs. Tadano doing the character designs for Eternal and Cosmos.

Source