The Christmas and New Year excesses are over and it's time to start the annual recovery process and ask forgiveness from the patron saints of liver recovery and blood toxicity. As a result, many people around the world will have adopted a "Dry January" as a New Year's Resolution, and now, halfway through the month, some may still be at it.
I started the tradition of taking a calendar month off alcohol once a year almost twenty five years ago now. Although I tend to not feel significantly different (an indicator to me that it's not the night before that's the problem but that basically I'm just rubbish at mornings) it's a habit I've kept up over the years if for no other reason than it provides me an element of moral high ground with myself later in the year.
The difficulty in Japan is that the concept of giving up alcohol if you regularly imbibe (remembering many Japanese are tea total) is somewhat alien here. There clearly must be a medical reason for it and January is as much a time of corporate nights out than is December so the question regularly arises.
To solve this I once came up with the briliant idea of explaining that I had hepatitis (which I didn't but you're not supposed to drink if you do). This didn't actually reduce the questions much however I was invited out significantly less for a while. Strongly suggest you don't use this one. These days I simply tell people I'm driving, drink my tea and leave it at that. They know I'll be around for a beer in February, and March, and April....