My rough translations of the photo captions, clockwise from top left are:

• SR-II
• Maruishi ST-I
• ST-II
• Maruishi SR-I

I believe that better labels might be:

• Sanko SR1
• Unknown Maruishi touring model
• Sanko ST1
• Maruishi S2

Sanko manufactured own-brand versions of its derailleurs for the Maruishi bicycle company.

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• Publisher: New Cycling
• Document: New Cycling May 1981 - '81 Derailleur Collection
• Date: May 1981
• Derailleur brands: Sanko, Maruishi
• Derailleurs: Sanko SR1, Sanko ST1, Maruishi S2 , unknown Maruishi touring model