Pilot Iroshizuku Tsukiyo (Moon Night/Moonlight, same difference) is a navy blue with a tad of warmth. According to this video (first found on FPN), Tsukiyo is the most-popular shade in Japan. Some categorizes it as a blue-black but on Lamy Safari fine, it get washed down a little to barely-deep blue.
A quality that I kept seeing in Pilot inks (not just Iroshizuku) is how well they flow and how easy they are to wash off, even on the finest nibs. The water-consistency means that they got suck right into (and feathers a little on) porous paper while having very noticeable shading on glossier paper.
Another bonus of Tsukiyo is that when used on a very wet nib (Lamy 1.9mm italic), there is a noticeable red sheen on the pooled part. Not the kind that requires you tilt the paper at a specific angle, under certain lighting or at a certain time of the day to be observed. The dry time was quick (by the time I am on the second line in the Rhodia pad paper, the previous one is already dried) and water-resistance is partial.
Scanned written review of Tsukiyo.