Luggage Forwarding vs. Storage – What’s Best For A Cruise?

My partner and I will be spending the day exploring Tokyo before our cruise leaves from Yokohama that evening. We'll be heading to the port from Shibuya, and we’re hoping to avoid lugging our bags around while we sightsee.

I was wondering – would it be better to use a luggage storage service near the station, or go with a same-day luggage forwarding service to the cruise terminal?

We're a bit unsure about the timing and reliability of luggage forwarding, since we obviously don’t want to risk our bags not making it onto the ship. Any advice would be appreciated, thanks!