In Persona 3, besides appearing on Sunday mornings as the host of Tanaka's Amazing Commodities, Tanaka appears every Tuesday and Saturday evening at Paulownia Mall, apparently taking a break from working hard as the CEO of his shopping network. After leveling up your Charm Skill to the rating of "Smooth" and handing over ¥40,000, Tanaka will take you under his wing and tell you several secrets including selling pills that act as placebos and give you glimpses into his past where it seems he was a poor child who got picked on in high school. By talking to Tanaka, the player also levels up the Devil Social Link.
If the player manages to max out his Social Link, the player can fuse Beelzebub in the Velvet Room.
In Persona 4, Tanaka's Amazing Commodities returns, and can once again be viewed on Sunday mornings. However, he does not otherwise appear in the game as a character, and the Devil Social Link is instead with Sayoko Uehara, a nurse at the Inaba Municipal Hospital. A subtle difference can be noticed in this shopping program vs Persona 3's, in that Tanaka is no longer wearing his sleazy smile in P4.