Mugen is a Kendama brand. They are JKA Approved. The seal is teal.
They are not in production anymore and they can only be found on auctions or through private sellers. They are quite expensive.
They are considered by many the best kendamas ever made due to their amazing lunar balance.
The manufacturer recently released a non-JKA Approved model named Mugen Musou(referred to as Musous). Along with the OG Mugens, they are both made out of beech wood, but while Mugens use a glossier paint style, Musous use a new paint formula that is much tackier and grippier in comparison.