Nintendo owns the Mariners. I thought Yamauchi relinquished his share a few years back, but I could be totally off base with that.
The guy is fucking nuts though. No doubt about that.
The guys on KJR still bring him up whenever they talk about corporate management of the team. He doesn't have any say in the operation of the team, that's what Howard Lincoln (yep, the guy from the old Howard and Nester comics from Nintendo Power) does, but he's still the majority owner.
edit: Huh. Some stuff says it's strictly NoA now, other stuff still has Yamauchi as being owner.
edit edit: Interesting stuff about Yamauchi and Yokoi:
Upon his return to Japan, Hiroshi Yamauchi decided to diversify the company. Some of the new areas he ventured into included a taxi company called Daiya, a love hotel with rooms rented by the hour, and individually portioned instant rice. All of these ventures eventually failed and brought the company into the brink of bankruptcy. However, one day, Yamauchi spotted a factory engineer named Gunpei Yokoi playing with a simple extendable claw, something Yokoi made to amuse himself during his break. Yamauchi ordered Yokoi to develop the extendable claw into a proper product. The product was named Urutora Hando (Ultra Hand) and was an instant hit. It was then that Hiroshi decided to move Nintendo’s focus into toy making. With an already established distribution system into department stores for its playing cards, the transition was a natural one for Nintendo. Hiroshi created a new department called Games and Setup, manned initially by only Yokoi and another employee who looked after the finances, and was situated in a warehouse in Kyoto for the purpose of research and development. Gunpei Yokoi was solely assigned to develop new products. Yokoi utilised his degree in engineering by developing what is now known as electric toys such as the Love Tester and a light gun using solar cells for targets. These electric toys were quite a novelty in the 60s when most other toys were simple in origin, such as toy blocks or dolls. Eventually Nintendo succeeded in establishing itself as a major player in the toy market.