Last year Sailor revamped their four season ink line, changed them into a smaller bottle thus raising steeply the per unit price, and added four more colours. (More details see here. On a side note, they seem to have changed the name of Fuji-musume into Fuji-sugata.)
It took me a long time but here it is, the last of the quartet: Yonaga. Yonaga is a pretty dark blue that writes very wet and smooth. It has some kind of water resistance. It sheens quite easily but the sheen itself is quite subtle. It's usually green, but it can also be red sometimes. When you make a splash of it there's a double sheen of red and green.
(photo taken in mild sunlight)
(Close up shot. If you look closely you can notice the green sheen.)
(on Tomoe River, with the other three)
(You're not mistaken if you think this ink looks familiar. To my eyes this ink is basically the same as another much rarer Sailor ink: Sailor Shosaikan Seiran: see reviews from Visvamitra and White_Lotus. Both these inks have that same kind of subtle sheen of red and green. If you love Seiran but find it hard to get, Yonaga is a much more accessible replacement.
Compared to Diamine Oxford Blue, Yonaga/Seiran has a bit more green.)
PS.: Visvamitra seems to find that Seiran dries out quickly on the nib. I can't say about Seiran but Yonaga doesn't have this problem for me.
Edited by Lgsoltek, 10 June 2018 - 11:02.