Luggage Storage at Shinagawa Station

Hi,
We will be reaching HND Airport at 6 AM. Plan is to spend day in Tokyo and then leave to Kyoto via Shinakansen train. We want to keep our bags, which are needed for Kyoto, while we will be roaming around in Tokyo.
After immigration formalities, I think we should be out at 7 AM. We want to ride train to Shinawaga station, drop luggage here at luggage storage and then start our day in Tokyo. In evening, we will come back at Shinagawa Station, collect luggage and get on Shinakansen train for Kyoto. I am trying to find luggage storage at this station, but couldn't see. If my plan is feasible, can someone help me with this information?
Thanks

I was just there last week looking for the same thing.
There are many coin lockers inside of the fare gates, which you probably don't want.
The only coin lockers outside of the fare gates are located towards the eastern end of the station, near the Shinkansen fare gates.

Check the previous post below

https://www.japan-guide.com/forum/quereadisplay.html?0+180010

or

here (JP website so use google translate) location of coin lockers inside/outside gate
https://coinlocker-shiori.com/jr-shinagawa-station/

We will be coming from Haneda airport, drop bags at luggage locker at Shinagawa Station and then leave for Meiji Jignu.
We will anyway come by train and further go by train. Will it not be okay to store bags which are inside fare gate ?
If not then, are eastern gate convenient as per our route plan ?

From HND to Shinagawa station, you will ride the Keikyu train line which is at the west end of Shinagawa staion. There is a separate fate gate you have to go through to the JR train gates. There are no coin lockers near the Keikyu gate. In order to use a coin locker inside of the JR line fare gate, you will have to pay a little to go through the gate. That's why I recommended to use the coin lockers outside of the fare gate, toward the east side of the station.

Understood.
After getting down from HND airport to Shinagawa at west side, is it easy walk to go to east side and after storing luggage, get another train towards Meiji Jignu ?
I am just trying to keep this information ready, so we will not get confused once there.

From Shinagawa station, take a JR Yamanote Line train going in clockwise direction (they call it "outer loop") and get off at Yoyogi Station. Then walk from there. See attached map.
https://maps.app.goo.gl/DjB4bmz8R4J28dg48

My #1 advice for everybody going to Japan is to learn how to use Google Map in Public Transportation Mode.

Yamanote line goes in a circle, so there are clockwise and counter-clockwise moving trains.

In your case, since you will take a JR train, you can choose a coin locker inside of the fare gate.

Thanks so much.

There is an assumption in the above replies that there will be AVAILABLE coin lockers to store your luggage. You did not specify the size of your bags, but for anything larger than a carry on bag there are far fewer coin lockers available and they are often full. In which case you are SOL.

Two alternatives.

...at Haneda, use JAL ABC or similar and store your luggage there for the day and pick them up there to go back on to Shinkansen.

OR

...at Haneda use Kuronekko or Sagawa or JAL ABC and have your luggage shipped directly to your hotel. It should arrive NLT the next day. This takes all of the hassle out of lugging luggage around...remember, you will have come off an international flight (jet lagged with little sleep), been out and about in Tokyo all day, then have to get back to Shinagawa or Tokyo to take the Shinkansen, get and lug your luggage on the train and then on the streets to your hotel, that is a lot to ask of anyone.

If you do the latter, the fees are very nominal and all the "heavy" lifting will be taken care of by the transport company, just pack one change of clothes for the next morning and your toiletries into a small bag which you WILL be able to find a small locker to store them in for the day at the station.

One more thing on this, arriving at 6a, clearing Customs and Immigration by say 7a or earlier, you are going to be smack in the middle of Tokyo commuting rush hour on the trains and in the train station. Carrying large suitcases on the train and through the train station passages searching for a locker will be a test of everyone's patience.

BTW. make sure to have a e-Suica or hard Suica hard card to pay for the lockers should you go that route, otherwise, you will need ~Y400+ in Y100 coins per locker.

Hope this helps.

Stan