Article by Nikkei shinbun (in japanese)http://www.nikkei.com/article/DGXLASDZ01HUF_R01C16A2MM8000/
Looks like those rumors were true after all.
Canon Electronics Inc., a Canon group company, is developing a small satellite launcher to expand their Space Technology Laboratory's offerings, possibly chasing a vertical integration approach from smallsat parts to launch services. Looks like they are doing the avionics, while the rocket body itself (looks like a solid rocket) is being built by IHI Aerospace.
Plan is to offer launch services in 2023?
Looks like released info is still limited.
0.5m diameter (probably applies to payload fairing as well)
2.6 metric tons gross weight
Performance/payload not listed yet.
This probably ties into other recent comments and work, such as the SS-520-4 nanosat launcher being a one-off informing design of other launchers. There were also rumors Canon Electronics Inc. was involved in TRICOM-1 that will be riding the SS-520-4 soon.
Canon Electronics Inc. is not exactly what one would normally call a space startup since it has big money and is self-financed, but it isn't old-school like MHI and IHI aerospace either.