I second Cirque Arachne.
It's hard to find something as skilfully written as Yagakimi. There's a couple of really good one shots I recommend (like this one ), but I reckon you want a longer story, so I suggest you check, if you haven't already, some of Morinaga Milk's work. Girl Friends is a community favorite, but I also recommend Secret of the Princess and this collection.
For manhwa, you should check out Ratana Satis. Some of her work has sensitive content, like rape (just like most of the stories published by Lehzin), so keep that in mind.
I know it's a bit against the rules to post outside links, but I'm going to ask for mods to let this one slide, because this webcomic is exactly what OP is asking for to fill the void of Yagakimi's absence.