Luggage delivery service from Osaka to Tokyo?

We will be arriving in Kansai International Airport and will stay in a Hotel in Osaka, staying for around 5 days. We will take the bullet train to Tokyo and stay there for another 5 days before going back home thru Narita Airport. We want to send our luggage to Tokyo frpm Osaka so we wont be struggling to bring them on trains and on our way to our hotel. Where can we send our luggages (service couriers?), and how many days should we expect it to be delivered? Kindly advise as this is our first time to visit Japan. Thank you very much.

Where can we send our luggage (service couriers?)
https://www.global-yamato.com/en/hands-free-travel/scene02.html
https://www.sagawa-exp.co.jp/ttk/english/service/hasso.html

There are delivery service counter available at most airport.
most your hotel can arrange for that. else you can find nearest convenience store and drop off your luggage for delivery arrangement. normally next day delivery but depends on your drop off time.
So give or take 1-2 days.

Hi! We are doing something similar but traveling from kyoto-osaka-tokyo. We wanna send a suitcase from kyoto-tokyo, how do we know if the company can keep our suitcase for the duration of days that it takes before we arrive in tokyo? Leaving kyoto 5th of april and coming to tokyo 10th of april.
Many thanks!

No problem. Yamato Kuroneko will keep it for 5 days. (Actually a bit longer even)