Osaka to Haneda to LAX, will I need to collect and recheck my bags in Haneda?

When checking my bag at Itami Airport the agent told me to ask the United staff at Haneda if I need to collect my luggage and recheck it there, does anyone have any experience departing from Japan with a domestic connection?

I know I’ll need to go through customs at Haneda but baggage is different everywhere. In America I would have to collect and recheck but in Europe I wouldn’t, I’m honestly surprised the check in agent in Osaka didn’t know.

by TastyLookingPlum