That's Nagoshi sitting in a tanning bed in Japan's Tanning Studio SOLE — which appears in-game. He's not only promoting his game, but tanning and promoting.
The brown game designer was introduced to SOLE by a friend-in-the-know. (Probably a golden brown friend.) So what's the appeal for Nagoshi? "I feel refreshed when my sweaty skin is tanned."
Apparently the idea of including SOLE in a game came about during a conversation with, wait for it, a SOLE staffer. Nagoshi confirms that going to the in-game salon does affect Ryu Ga Gotoku hero Kazuma Kiryu. No word whether overuse causes skin cancer later in the inevitable Ryu Ga Gotoku sequels.
For those in the dark about Nagoshi's browning, read this.