Your new pair are still kittens, right? My brother's cat -- the one that sometimes hangs out at my place -- was an eight week old kitten when he first arrived, and while a couple of my cats (Ricky and Max) loved him, the others wanted nothing to do with him. They acted towards him very much like your Takibi does towards your kitties. However, once he got close to adulthood, they treated him like all the other cats. I think some cats just don't like the unpredictability of kittens, but once they grow up they get along fine.
A few things I do to help keep the peace:
-- I don't let any of the cats get too pushy with another cat. Oscar doesn't really like LBC (Little Black Cat, my newest addition) and will sometimes bully LBC. He'll stalk LB or just sit near him and stare at him. LB doesn't like this and will growl (he knows I'll come to his rescue when he does that). Now all I have to do is say "Oscar!" in a certain tone, and Oscar will leave LB alone and go somewhere else. At first I did have to shoo Oscar away or put him in another room, but now he knows he's crossed the line and will just leave when I tell him to. (The dog (Zeke) likes to reinforce what I said -- he'll run over to Oscar, bark, and give him a shove with his nose. Drives me nuts sometimes, but he's a heeler and he's decided that keeping the cats in line is his job.
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-- everyone gets special attention, especially the cats who seem most put out by the new addition. When they get attention from me they don't seem as concerned about the new cat or cats.
-- I also try not to let the new cats infringe too much on the established cats territory. For instance, if there are places your established cats particularly like to sleep, make sure the new cats don't take those spots over completely. You might have to put them in a different room for a few hours each day.
Overall what I have found is, if given enough time, the vast majority of cats will accept new cats into the household. They might not all be best friends, but with several cats, they don't really have to be best buddies with everyone.