From Sega Retro
Yukawa strangely became an overnight success in Japan after appearing in a Japanese Dreamcast commercial. In it, Japanese kids make fun of him while praising Sony and their console, the PlayStation. After informing his work colleagues and being beaten on the street, he makes a stand for all things Dreamcast and attempts to set the record straight. Yukawa was not an actor, but his performance was so good that Sega were swamped with letters of praise, and so he would appear in numerous Dreamcast adverts over the console's lifespan, even apologising personally for the lack of stock in Japan during the first few weeks after launch (and being quick to point out when more stock was available in the coming months).
Though perhaps not as popular as Segata Sanshiro, Hidekazu Yukawa was popular enough to be featured on prepaid convenience store cards and photo sticker booths. He had his own website and features in the game Yukawa Motosenmu no Otakara Sagashi. He has also appeared as cameo in a number of Dreamcast games, including What's Shenmue in which he encounters the protagonist Ryo and needs to be chased through a series of quick time events, and Sonic Adventure's DLC, where he appears on the QUO cards hidden around Station Square and Mystic Ruins to be collected by the player within 10 minutes.
For a short period there was even a set of Yukawa-branded Dreamcasts for sale in Japan.