Dunno if that could be considered Yuri considering there is basically no interaction between the two of them.
Anything goes, I guess.

The last panel.. T.T

That was a good read.

Is there any more Koishi doujin by Personal Color?

Unfortunately, no, even in untranslated doujin.
It is kind of a shame. This Koishi seems a little different from a normal Koishi.