From what I remember, this is a flashback when Yuuko remembers the last elections. Who the hell are all these chicks? It looks like the one in white and gingham, sitting down may be Lemon-chan (or is that Love-tan?) and the one behind her may be a Sayaka.
Using my horrible time line skills, if Yuuko is 18 in season one (Stellar Year 0048) in Stellar Year 0044 she was 14 and that would probably make these kenkyuusei (if thats what they are - the girls in white/blue anyway) the 73rd generation.
Edit: Thanks for the correction. Yuuko is 72nd Generation (meaning she was 13 here). Judging by different outfits, we’ve got successors in red (Sae the 9th?, Sayaka -at the back?- and maybe a Yukirin)