The Minicube (QB-V850MINI[L]) is a JTAG tool that was common for that
device, out of production for some time now but if you can find it,
would do the job. Could be used with the old debugger IDE (ID850QB) or
the newer IDE CS+ for CA/CX (free to use for debug-only applications).
Uses a 20pin connector.
The Minicube2 support the serial programming interface and can be used
with the modern Renesas Flash Programmer (RFP) v2.05.03 which supports
V850, or the predecessor tool WriteEZ5. Uses a 16pin connector.
Finally the E1/E20 debuggers support V850 devices, both for JTAG and
serial programming mode, using CS+ for CA/CX and RFP, respectively. The
E1 was the low-cost debugger ($150USD) but it has been out of production
for over a year now. Still can be found occasionally on Ebay and
sometimes you will find an old Starter-Kit at an electronics distributor
with the E1. The E20 is still available but the cost is quite high for
a Renesas on-chip debugger ($1000USD). These use a 14pin connector.