Originally Posted by maotd

Nope. Just a DMM code girl to buy with NG on Nutaku. No serial code on Nutaku since... more than one year? Something like that.

Looking through the edits on http://harem-battle.club/wiki/Flower...G:Serial-Codes, it seems the last serial code we had was between October 30 and December 7 last year.
Most of the serial codes were for 4* girls though, so people who played for more than two months would maybe grab them for completionist purposes (having a 5 skill 4* on your bench is nicer than a 4 skill 4*), but didn't really actually need those girls anymore.

The most interesting rewards were a rainbow skillbloom (Fakebook serial code) and Chocolate Cosmos (Anime Expo serial code).