Artist as tagged doesn't seem to match. Style is different, and the artist for the doujin this is from is listed as mt, it says that in the source name too. So I doubt this is halcon/harucon_(halcon).

So do you think this is also nanamomo_rio?

No, this isn't nanamomo rio's, it would be on his/her pixiv if it was. Artist appears to be mt, but there's no tag for it here yet.

https://www.pixiv.net/users/19848350

An explanation: First tried to set artist tag to mt, but noticed there is already such a tag. But none of the art matches to any art of mt(mt_(myvva) I've found out there.
Little research and found this piece is listed under mt_(myvva) on danbooru (however that links to different pixiv(?)) so created artist tag mt_(myvva) instead.
About the artist mt found here, found out those works are listed under mt_(ringofive) on danbooru

There's still a chance they're the same artist(?) so please correct if this is wrong.

Edit; Actually, seems there's tag mt_(ringofive) here which also matches mt_(ringofive) on danbooru.
Based on all that I assume mt and mt_(ringofive) here are same, but mt_(myvva) is a different one?

Edit4; Just registered on pixiv to take a closer look, and it's now certain this image is associated with the artist mt_(myvva) listed on danbooru(twitter checks out also).
Doujins attached to the artist seem to be all under the circle +Elegy, can't find any tag for it here.

The word 'myvva' probably comes from the artist's old pixiv feed;
https://www.pixiv.net/stacc/myvva