While looking through SG-1000 ROMs, the name ELS was found in Yamato:
"BY ELS SHINKAWA-BL.,204,TAKAIDO,TOKYO,TEL 03-331-7608"
"1983.07.07 E.L.S ;HEAD OFFICE : SHINKAWA BLDG.,2F,204,1-29,TAKAIDO,NISHI,1-CHOME,SUGINAMI-KU,TOKYO,166,JAPAN ; PHONE : 03 - 331 - 7608"
Presuming ELS was a company, the investigation continued. It was later noted that Yamato, Sega Flipper, and Monaco GP used the same font, so a code comparison was performed. All three games came up, as did the Pachinko games and Star Jacker. It turned out that these games also used this unique font. Perhaps it's all just a big coincidence.
ROM text in Monaco GP:
"MONACO GP9/15 -1983 VERSION 1.0 24K" "PROGRAMED BY Y.KAWAMURA & M.KIDOOKA"
ROM text in Pachinko and Pachinko II:
"---- PROGRAM BY < K.O > ----"
Then there's the arcade games. One of the ROMs in Yamato contains the following text:
"SECULITY BY M,MIZUNAGA. PROGRAM BY L'Y:] TEL 03-331-7111 25 MAR 1983 USA TYPE"
The telephone number seems awfully close to the one in the SG-1000 Yamato ROM.
It's been noted that Top Roller and Yamato were by the same developers.
- Top Roller (Manufacturer: Jaleco)
- Yamato (Manufacturer: Sega)
- Monaco GP (JP/EU Publisher: Sega; AU Publisher: John Sands; NZ Publisher: Grandstand)
- Pachinko (JP Publisher: Sega)
- Pachinko II (JP Publisher: Sega)
- Sega Flipper / Video Flipper (JP/EU Publisher: Sega; AU Publisher: John Sands; NZ Publisher: Grandstand)
- Star Jacker (JP/EU Publisher: Sega; AU Publisher: John Sands; NZ Publisher: Grandstand)
- Yamato (JP Publisher: Sega; AU Publisher: John Sands; NZ Publisher: Grandstand)