At my first sip I thought for sure I had a dud product, it tasted like regular kirin milk tea with the addition of funky grapefruit. Automatically I assumed it must have passed it's use-by date or since I had made a buffoon of myself in the convenience store by dropping it on the ground that perhaps I had wrecked the can.
But no, apparently not. After a quick google I find that yes indeed it does have a bitter taste which some review as pleasant, but honestly I can't believe it. It is still sitting on my desk with only one sip taken and I'm not sure I want to go for another, but I must!
I check the can again for a picture of grapefruit, but find no such reference. At first swilling it around in your mouth it could be described as a really burnt flavour which I suppose is espresso-ish, but really, it seems overdone and unpleasant and now I just have a grapefruit-tea aftertaste.
If you're adventurous and/or bored, go for it. I gave it a 1/10 for satisfiction(sic) in the knowledge that it was not expired, damaged or grapefruit inspired. I found mine on the discount table and was sure I was going to be spraying it out after the first sip due to it being expired.