Kigen ® [product name] and/or [approved noun]
e.g. Kigen ® SIM OS
Kigen ® eUICC OS
Kigen ® service
Kigen ® OTA (over-the-air update) service
Kigen ® RSP (remote SIM provisioning) service
Kigen ® SM-DP (subscription manager - data preparation) service
Kigen ® SM-SR
Kigen ® SM-DP+
Kigen ® RSM (remote subscription manager) service
Kigen ® UI (user interface)
You do not always have to use an approved noun after the Kigen trademark if it is followed by a product name.