SegaSonic the Hedgehog was the name used for branding of the Sonic the Hedgehog series in Japan for the most part of the 1990's.
It started when Sega filed a trademark application for "Sonic" in December of 1990, several months before the release of the now-famous Mega Drive game. In Japan at the time however, trademark applications could take up to three years for approval, and arcade rival Taito already had the arcade game Sonic Blast Man. Likely to avoid conflicting with Taito, Sega used "SegaSonic" for branding of its arcade games in the meantime. This lead to Sega's arcade games such as SegaSonic the Hedgehog, SegaSonic Cosmo Fighter and SegaSonic Popcorn Shop to use the SegaSonic branding. It was also used for merchandise of the series such as clothing, household items, and plushes, likely for consistency.
Finally in 1996, Sega's original application was approved for use with arcade video games. Sonic the Fighters is one of the first Sonic arcade games with the normal "Sonic" trademark. After this, the branding was no longer needed, but continued being used mainly for merchandise until at least 1998. Likely due to the series being reinvigorated by the release of Sonic Adventure a few months later, the SegaSonic brand was no longer needed, and was discontinued.
A set of plush dolls were made based on Sonic the Hedgehog, and they were available as prizes in machines such as New UFO Catcher and UFO Catcher Mini. The tag on each plush has the Japanese Sonic 1 logo, and the set consists of Sonic, Doctor Eggman, Pecky, Pocky and Flicky.
This is the second set of Sonic UFO plushes and are the first set to be of the SegaSonic brand.
The set consists of the same characters as the previous set, except the Sonic logo on the tag of each plush is replaced with the SegaSonic logo. The plushes are slightly different from the previous set as the animals are larger, and the Sonic plush has new limbs and rubber shoes. Sonic's hands can also stick together.
This is the third set of UFO Sonic plushes, and once again they all resemble the previous set. This time however, the Sonic plush is completely remade, and comes in a sitting version and finger posing version.
The theme of this set is dressed up versions of mainly Sonic and Tails, and they are all made based on the way the Sonic plush is in the previous two sets. This set included possibly the first plush of Amy Rose.
This set contained only three plushes. Oddly the theme was about Rocky, and a plush of Sonic and Tails were also made. These plushes are different from ones in previous sets as they are bigger and have a fuzzier material.
This set only contained two plushes, this time just Sonic and Tails. Sonic is seen with a Soccer ball and Tails with a fan of sorts. Like the Rocky set, they are also bigger than the usual UFO plushes and are have a fuzzy material.
This set debuted the first plushes for Metal Sonic, Espio, Bean, Bark, Fang and Super Sonic. This makes these plushes extremely sought after and valuable. Seeing as the set contains so many plushes, along with half of them being the first plushes of characters, the set is well known and distinct from other Sonic plush sets.
This set contains plushes of Sonic and Tails, but with a theme of pastel colors. There's two plushes of each character, one being a pastel version of the characters' colors and one being completely white. This set is unique and distinct for being the first Sonic plushes to be available completely white.
This set contains plushes of Sonic and Tails, both being about 15 inches tall. These were the last plushes made for the SegaSonic brand as they released in early 1998, which is the same year Sonic Adventure later released in Japan. The tag features unique American styled art of Sonic, despite only being available in Japan.