Famicom, Famicom Disk System and PlayChoice 10
© Konami FC 21/02/1986, FDS 08/04/1988 -- ¥?
In stage 4, pressing Down+B on the place shown in screenshot makes Vic Viper appear.
Collecting Vic Viper will give you 5000 points. Even if you miss it, you'll still get 1000 points.
Also make an appearnce in this game
Surprisingly, this game came out BEFORE the Famicom version of Gradius!
Thanks to DeadMario