EK-RA8D1 to RTK7EKA6M3B00001BU Display Adapter
Overview
The EK-RA8D1 to RTK7EKA6M3B00001BU Display Adapter is an open-source hardware converter PCB that adapts the EK-RA8D1 Parallel Graphics Expansion Port (J57) to the RTK7EKA6M3B00001BU display shield.

EK-RA8D1 to RTK7EKA6M3B00001BU Display Adapter (top)

EK-RA8D1 to RTK7EKA6M3B00001BU Display Adapter (bottom)
Programming
Set --shield ek_ra8d1_rtk7eka6m3b00001bu
when you invoke west build
.
This shield is just a converter, so it is usually used with RTK7EKA6M3B00001BU shield.
For example,
# From the root of the zephyr repository
west build -b ek_ra8d1 --shield ek_ra8d1_rtk7eka6m3b00001bu --shield rtk7eka6m3b00001bu tests/drivers/display/display_read_write