For whoever has grown up in France like me (but I assume it’s true for many other countries too), an underground passage in town is very often synonymous to dirt, unholy smells, graffiti and they’re not always that safe.
So you can imagine the contrast compared to this:
If you’re curious as to where you can find it, it is located in the North-West corner of Chūō Kōen, at the intersection of Chūō-dori and Shido-kaido.
Now, I’m not gonna lie. This is the only one underground passage in Takamatsu (to my knowledge) that is that good-looking. However, all the other ones are safe at any hour of the day or the night too.