There have been some questions regarding the history of Toaplan as a company and about some of the early games that only have a Taito copyright.
The name Toaplan means "East Asia Ambition" or "East Asia Project".
Here is a translation of the story of Toaplan by Tatsuya Uemura, one of the Toaplan musicians:
Tatsuya was in college and worked for a music studio, but he left the studio and lost his job. At this time, the beginning of the 1980's, there was a small game maker named "Orca", who were advertising "Recruiting Computer Sound Creators!!".
Tatsuya's dream was to be a musician, and he was offered a job at Orca where he studied programming and game development. At that time Orca had already gone bankrupct, but Tatsuya could still work there for about half a year.
The Orca free ride ended when the Yakuza came into the office and shouted "Where's the fuckin' boss!!" The company could stay in the building for a guarantee deposit. But when the money ran out, they got kicked out of the building.
After that, Orca's development team set up a new company they named "Clax". Clax only created one game, "Gyrodine" (Taito 1984). This game is the origin of the Toaplan games, but Clax also went bankrupct because of financial difficulties.
The chief programmer and the designer of Orca and the man who made Gyrodine went to one company. The name was "Toa-Kikaku" (which means Toa Planning).
Before the Clax programmers joined Toa-kikaku, they distributed arcade games, and did installing and maintenance, and so on. These three men made started a software development section of Toa-kikaku and it was renamed Toaplan. Tatsuya was approached by Toaplan, but he was finishing a game for another company. After finishing that game he went to work for Toaplan as a musician and programmer.
One of the Clax programmers, Orca's chief designer, is currently the president of Cave. Orca's chief programmer is now president of another game company which is a subcontractor of Takara (Japanese top toy maker).
The first known game from Toaplan is ("Jong-Ou" / Mahjong King) from 1984 which was sold to SNK. Toaplan made a couple of more Mahjong games in 1985, ("Jong-Kyuo" / Mahjong Mania) and (Mahjong Sisters).
Toaplan began their long-running work with Taito as a subcontractor, creating a bunch of games like Tiger Heli, Get Star, Mahjong Sisters and Slap Fight etc. These games usually have a TOA entry in the last name of the hiscore table. The first Toa game with Taito is Tiger Heli.
Eventually the Toaplan logo appears on title screens in games, probably starting with Hellfire (1989).
In 1994, while working on "Otenki Paradise" (Snow Bros 2) Toaplan goes bankcrupt. Many of the employees start working for newfounded Cave which creates games like Steep Slope Sliders for JVC, but also shoot'em-up games like Donpachi and Dodonpachi which are only released in Japan by Data East. Feveron is a more recent Cave shoot'em-up, looking very much like something Toaplan would have came up with.
Another ex-Toaplan company is Gazelle, they've created a Final Fight type game of "Sailor Moon" which is a high quality fighter, with Capcom like graphics, and another game called "Quiz Sailor Moon" which also has good graphics.
Takumi Corporation developed 2 (Ultimate Tiger 2) on a Taito F3 board (arcade machine hardware type) after Toaplan's bancruptcy for Taito.
An interesting fact is that Raizing has created Toaplan-like shoot'em-up games on "Toaplan hardware", and this company started a bit before Toaplan went bancrupt.
Demon's World came in originally to the US as HORA STORY. When Catalina Games licensed it after Romstar rejected it, the rounds were shuffled so that the music from round 1 went to round 4.
Teki Paki came to the US under the neat name of THE BRAIN WASHING GAME.