I bought a sample each of Pilot Iroshizuku Ku-Jaku and Syo-Ro to compare them with each other. At first, I thought that I might have received the same sample twice, one of them being mislabeled. Nope.
These inks dry to the same blue-green teal colour on both white and ivory, Japanese and European, papers I’ve used. They go down differently, Ku-Jaku being slightly bluer than Syo-Ro, but at the end of the day, I can’t tell them apart once they dry. Also, they are very similar in colour and behaviour to Diamine Schubert from the music collection. I don’t have Sailor Jentle Yama-Dori or the Shikiori equivalent for reference, though.
Ku-Jaku has red sheen and a dark outline where the ink pools in heavily saturated areas. The ink dries pretty quickly and is capable of shading in the right pen and paper combos. I’ve observed none of the nasties; the ink is well-behaved and coats the nib tipping rather well.
Syo-Ro behaves similarly to Ku-Jaku—sheen, shade, no nasties—and is maybe a bit darker in swabs, but during normal writing, with the same pen… meh.
There is nothing wrong with the quality of these two inks, so it doesn’t warrant having a star removed; I just don’t like these colours.