As a pseudo-sequel to the Buu Saga, Dragon Ball DAIMA has further extended Majin Buu’s family tree. This expansion comes courtesy of Dr. Arinsu, the older sister of Nahare, the only surviving Supreme Kai following the original battle against Buu, and Degesu, the right-hand man of Supreme King Gomah. The newest Dragon Ball anime has retconned Arinsu to have been present on Earth during the Z-Warriors’ battle against Fat Buu. While there, Arinsu collects a piece of Majin Buu’s essence, after Buu was blasted into thousands of tiny pieces by Vegeta’s Final Explosion.
A scientific genius who dreams of ruling over the Demon Realm as Supreme King, Arinsu enlists the help of Mabra to help her grow her essence of Majin Buu into fighters even stronger than Buu. To ensure loyalty, which Buu never had, Arinsu’s Majin aren’t solely made from Buu’s essence, but from Arinsu’s saliva, and Saibaman seeds. While the new Majin are most certainly loyal, it’s equally clear that they don’t live up to Arinsu’s expectations of being more powerful than Buu.
The first Majin Arinsu and Marba create is Majin Kuu. Despite making an impressive first appearance, Kuu proved himself to be nothing like what Arinsu was hoping for immediately afterward. Kuu is whiny, overly silly, cowardly, and not even strong enough to combat the Tamagami. Kuu’s most positive quality only comes out after Arinsu realizes he isn’t going to cut it, and uses all the essence of Buu she has left to create Majin Duu. For all his faults, Kuu loves his little brother, and is supportive of him from the moment he’s born. Duu himself is largely non-verbal and obsessed with eating, but he’s also infinitely more powerful than his little brother, capable of holding his own against Tamagami 1.
While they aren’t strictly canon, it’s also worth noting that both Dragon Ball Online and Dragon Ball FighterZ both expand upon Buu’s family tree, and that both of these video games can boast having had direct involvement from Akira Toriyama. In Dragon Ball Online, Fat Buu is revealed to have once again reproduced asexually, this time to create Miss Buu. Meanwhile, in Dragon Ball FighterZ, the main villain of the game, Android 21, bares the appearance of a Majin because Buu’s cells were used in her creation.
Majin Buu is a weird, ridiculous character, but that’s part of why fans love him so much, and it’s only right that his family tree is equally strange. Most of his familial relationships are non-traditional and difficult to describe, especially with several of his family members being alternate versions of himself. It’s unclear how much longer Dragon Ball DAIMA will go on but, hopefully, it won’t conclude before Buu gets to meet his true mother, his new pseudo-children, and any other Majin Arinsu manages to cook up before the anime reaches its finale.