The company produced a line of character merchandise around gift-giving occasions. Hello Kitty was added to the lineup of early Sanrio characters in 1974 and the first related merchandise was released the following year. The popular feline whose mouth is usually invisible has had both peaks and drops in sales over the years, but always has been the highest contributor to Sanrio's sales. Other notably popular characters through the years have been "The Little Twin Stars", "My Melody", "Keroppi", "Tuxedo Sam", "Badtz-Maru", "Chococat", "Cinnamoroll", "Sugarbunnies", "Jewelpet" and "Wish me mell". Sanrio constantly adds new characters to its lineup. Specific characters are rotated in and out of active production. For a short time, Osamu Tezuka's baby unicorn character Unico, who starred in two feature-length anime movies in the early 1980s, was also part of the Sanrio empire; however, the rights to Unico shifted to Osamu Tezuka's own company after Tezuka's death in 1989.