乙 — the latter, duplicate, strange, witty

乙女おとめたちは 彼かれに 胸むねをときめかす。

He makes young girls' hearts flutter.

この二つの作品は 甲乙こうおつ 付つけがたい。

Between these two works, it is hard to say that one is better than the other (literally: differentiate between them).

その直後に目に涙を浮かべるなど一貫して純情な乙女として描かれている。

Otherwise, she was consistently described as a pure-hearted young lady who made a misty gaze immediately after that.