Hidekazu Yukawa (Kanji: 湯川英一, Rōmaji: Yukawa Hidekazu), most commonly known as Mr. Yukawa or Mr. Sega, was the Senior Managing Director of Sega during the Dreamcast era.
Ryo Hazuki looks for Mr. Yukawa. Once he finds him, Yukawa runs away thinking he is the attacker that wants the "disk" so Ryo chases him and they eventually end up at You Arcade. Ryo then saves him from the attacker. After that, Ryo and Yukawa talk for a bit then Yukawa wakes up and realizes it was all a dream. His desk is surrounded with unsold Dreamcasts. He looks up and sees a poster of Shenmue on the wall and then makes a big effort to help sell the dreamcasts.
Ryo can obtain Mr. Yukawa Capsule Toys as a prize from the raffle at the Abe Store. Once he obtains them both then goes to Takara Sushi on the 9th of any month after 8pm he will encounter Yukawa there and they will talk about their last encounter. This dialogue was removed from the English versions of the game. Also on the day after Nozomi tells Ryo how she feels about him, after 11:00 pm, Ryo can see Yukawa at Bar Yokosuka having a drink. He can also be seen on battery boxes at the Tomato Convenience Store in Dobuita.
- Yukawa's zodiac sign is Taurus and he has a B blood type.