In the Cop Craft wikia it's mentioned Tilarna is 18 years old. How about Kei Matoba? Is it mentioned in the light novel how old is he?
His age is never explicitly revealed, nor has the current year or date of the in-series world ever explicitly mentioned or revealed.
We have his birthday as June 18th, 1993. We know he was part of a peace keeping mission about 10 years from the start of the series and that the gates opened about 15 years ago.
If we assume it's the current year (2019), with touch screen phones et al, 2019-1993 = 26. Kei was 16 when he did his peacekeeping excursion.
By looks alone, we can maybe assume him to be mid/late 20s to mid 30s, the average age range of hard-boiled detective character archetypes.
No date is explicitly depicted in the anime thus far it seems. Not even on the porno magazines.
Because the anime changes the ages, Tilarna is 20 Earth years old in the novels, it's unsure what else has changed in regards to the original source vs the anime.