The laser for countering missiles is currently in the planning stage, while lasers for countering small drones with 10 kW output and for countering UAVs and mortar shells with 100 kW output have been manufactured.
The anti-missile type is expected to receive funding and enter the research and development phase after the completion of the 10 kW class model, likely around 2025 (R7) or later.
ATGMs would certainly be a good defensive measure against armored targets, however, I think that because they are meant to be deployed with the Rapid Deployment Regiment, Japan would prefer them to not fight tanks.
Also, ATGMs would cause the testing phase to be longer, and Japan is trying to adopt the ICV as soon as possible.