Mame (Rex in the English version of Yakuza 3) is a dog in Yakuza 3 and Yakuza 4 adopted by Sunshine Orphanage.
Yakuza 3
Mame is an abandoned puppy found by Izumi. Mame reminds Izumi of a dog she once owned. She convinces Kazuma and Mikio to try and help her catch and train Mame. If the player chooses to, they can actually teach Mame a few tricks.
Yakuza 4
While on a walk with Haruka, Mame pulls away and runs to the beach in front of Sunshine Orphanage. This is when they both find Saejima washed up on shore.
Appearance
Mame is a shiba inu, a small dog breed native to japan. As typical of his breed, Mame has a curled tail and a white & cream-colored coat of fur of short-to-medium length (although shibas can also come in a variety of colors).