From Sonic Retro
Has Bean is the main character of both incarnations of Dr. Robotnik's Mean Bean Machine. He is an export of a major character from the Puyo Puyo franchise, Carbuncle; he plays a more important role there than he does in the Mean Bean Machine games. Exactly why Compile and Sega left him in Mean Bean Machine is unknown, however to compensate, they changed his name and give him a new backstory related to these games.
According to the manual he was once an inhabitant of Beanville but was transformed into a robot with Dr. Robotnik's roboticizer. During the game he can be seen next to the score (Mega Drive version only), watching as the game commences. Despite the game's links to Adventures of Sonic the Hedgehog Has Bean has never appeared in the series.
It is of note that the instruction manual states that matching 4 beans together sends the Beans to the Mean Bean Machine, which then leads to what is called a "horrible fate". The instruction manual also states that he became "un-jolly" after being roboticized. This in combination with the fact that Has Bean is controlling the descent of Beans dropped in his dungeon means that he is essentially another henchman of Robotnik.
|“||Has Bean used to be one of the jollier beans in the village... Until Dr. Robotnik changed him into a robot. Usually he prefers to clown around on the sidelines, but he hasn't forgotten his humble past. Occasionally he'll drop into your dungeon and take a little walk. Any beans he walks over change to the same color and disappear.||„|