ツワブキ社長 President Tsuwabuki
Steven Stone (son)
Prior to the RS Arc, Mr. Stone and his son Steven were aware of the danger posed by teams Aqua and Magma and prepared for what was to come. They devised the plan to have Captain Stern build the Kaien I so that Steven could seal the Seafloor Cavern, thus preventing the teams from reaching Kyogre and Groudon; they also had the backup plan of Steven unsealing Regirock, Registeel, and Regice in case Groudon and Kyogre were awakened. They needed to translate the old tablet to do that, which Mr. Stone achieved.
Team Aqua tries to steal his submarine mechanical part, which he was delivering to Slateport City under the guise of being on stroll. Team Aqua traps his Castform in a fountain and intend to pose as repairmen, luring him away. However, Sapphire unintentionally interferes by rescuing Castform, forcing Team Aqua to attack Mr. Stone directly to steal the machine part, seriously wounding Mr. Stone in the process. Before being brought to the hospital, probably by Maryann and Tyler, Mr. Stone gives Sapphire a letter to deliver to his son, Steven.
Mr. Stone seems kindly but very unassertive, telling Sapphire not to try to rescue Castform because the authorities were on their way, but he says it in a rather meek, unconvincing manner. The fact that he disguised his delivery to Slateport as a stroll is indication of a more devious mind, though.
Castform eventually ends up as Ruby's Pokémon, who nicknames her Popo.
Mr. Stone is shown to regard his son as an adult capable of making his own decisions and risking his life for a worthy cause.