Glad to see that the US military seems to be cooperating with the investigation, at least.
The US military's refusals in the past to hand over one of their own hurts their credibility and their soft power. No one is above the law, not even the military.
I was stationed at MCAS Futenma on Okinawa. The US shows no mercy when it comes to crimes against the local residents. Usually the Japanese legal system gets them first then after they spend time in Japanese prison they face the military legal system. We get a whole week of classes when we first get to the island about Japanese culture and they make sure to impress upon how fucked you will be if you cause an international incident. Even minor offenses such as underage drinking are dealt with very harshly. There were two Marines from my squadron sent to Corrective Custody Unit for drinking underage at an off limits bar.