Yes, that appears to be a 15 clone. Sometimes these Japanese clones will have a JA and/or JC with a number after the JA/JC. There is someone that has been keeping a list of various badged names and possibly which manufacturer is associated with that number.
http://www.doubleveil.net/zssmp/resources.htm There are many threads here on QB about clones. Here are a couple
Will the Real 15 clone please stand up and
Can anyone tell me more about this machine? (electro grand)
I have a 15 clone, that the "made in Japan" was on the back pillar and I did not see it until I took the motor off.
ETA - a manual can be found at
http://ismacs.net/singer_sewing_mach...ion-manual.pdf It threads a little differently than the 15-90 & 15-91.
Janey - Neat people never make the exciting discoveries I do.
Not affiliated with off-site link(s)