INTERPOL is basically an information sharing organization that connects police forces in different countries.
It has no authority on of it's own. It's not a police force or law enforcement agency. It can't issue warrants or make arrests.
Basically, they are the holders of a bunch of databases that each country's official poc (national coordinating body - "NCB") can query, enter data into, and receive notices from.
Notices come in different colors. A red notice is an information alert by the host county (Japan in this case) to other national police forces that a subject is wanted for prosecution. Other country's police forces can choose what they want to do with this request. A red notice is not an indication of guilt.
Most red notices are restricted to only law enforcement officials and the subject/public won't even know about them. This makes sense if you are actually trying to capture someone.
You make a notice public for two reasons.
1, you need the public's help in finding someone. That's not the case here since we know where the target is.
2, you are making a political point.
I suspect Japan's legal and law enforcement community was seriously embarrassed. If they actually wanted to/thought they could capture him, they would have reached out discreetly to other agencies via a law enforcement only read notice/and or other diplomatic means.
INTERPOL is a fascinating international organization and it's interesting to watch all the geopolitics play out.
[1] source: occasionally work with INTERPOL as a consultant/subject matter expert