Hand carry a bottle of liquor on JAL?

I've been told to buy back a bottle of liquor. This will be my first time needing to bring back liquor so I've no idea on that. Is it possible to hand carry the bottle if I buy it from outside the airport or if I buy from the duty free shop in the airport?

I assume you are flying out of Japan on JAL, since you say "buy BACK a bottle."
https://www.jal.co.jp/en/other/info2006_1219.html

Which means, if you buy a bottle outside the airport, unless the bottle is 100ml in capacity at maximum, you cannot bring it in as a carry-on. So if you buy one before you go to the airport, pack the bottle securely into your suitcase and check it in.

You can buy one in duty-free and carry that with you on the international flight. But if you have a connecting flight after you reach the first arrival airport, the same restriction applies.

Pretty much all airports/airlines only allow 100ml max of fluids.

So if you buy it outside the airport, it has to go in your checked luggage.

Once you are past security check etc. Then you can purchase fluids that can be put into your carry on.

In addition, bringing a glass bottle onboard could be problematic regardless of capacity, since it could be viewed as a dangerous item.

To be safe you should put any bottle in your checked bag inside a waterproof plastic bag.

I was asked on a couple of trips if the bottle were in such a bag when they x-rayed my check-in bag at check-in. I said "no" once and they made me take it out and I had to go find a bag to put it in (found some at an airport convenience store). One time I just gave 2 bottles of shochu to the owner of the Craic & Porter who went with me to the airport instead of looking for a "biniru baagu." And once, when I had them all bagged up, they didn't ask.

I managed to store 7 bottles of sake (5-300ml and 2-720ml), 2 bottles of gin (750ml) and a six-pack of beer in my checked baggage (suitcase and gym-bag) and none of it was in water-proof bags. I just used clothing as cushion and it arrived in the US intact.