It is fiction. I am going to wait to see if he is drunk or tipsy. He is something because of his eyes. He is not faking the redness around his eyes. He could be drunk, it is possible. It is possible he may be tipsy and faking some things. But he is not sober.
You can take parts of the story for both, drunk or tipsy while faking some of it.
But it is possible to get drunk or tipsy from that gulp of alcohol depending on the person. It is his tolerance and sensitivity to alcohol. You can have 5 people that is 6'4" and a MMA fighter and they will all act differently. Some could drink 2 bottles and not be drunk. Some could take a gulp and be drunk.
"Soju itself is usually 14-18% alcohol content so it's more than your average beer and wine and it will creep up on you."
While it is true that alcohol affects individuals differently, the amount of alcohol in a standard shot is typically not enough to cause significant intoxication on its own. However, it's important to note that individual tolerance and sensitivity to alcohol can vary.
Not my cutie patootie having his little heart broken