Japan does have a very soda-like liquor sold in convenient store though. Not very sure if someone who have never drink before and are very young (bitter taste bud decrease with age, so the older a person, the less they perceive bitterness, and, in turn, alcohol) can notice the difference, but to me who is old, they are practically flavored soda, but they can still get you tipsy with enough dose, still, especially if you were to chug it down like soda.
Try searching Horoyoi. You will see there are all kinds of fruity, refreshing flavors in a very cutesy, friendly looking cans since they're marketed towards women. But the glaring hole in the story is that, these drinks always, ALWAYS, state clearly they are booze (not confirmed, but very certain it is required by law so probably no brands out there not plastered the word liquor on their can), and how sheltered you have to be to not know these cans are booze, when you can find them everyday in the booze fridge next to, but clearly separated from, the normal soda?