aaahh, i love the two new Gumi's songs, Green Straight and Uso to Diamond. Her voice is tuned so well there. <3

As for Kyougenkuse (Nekomura Iroha x Miki), I think the slightly deeper voice is Iroha's? I've listened to her other songs and demo before, and her voice sounds like the deeper one's. (Many people commented on how it doesn't suit her design, but strangely enough her voice starts to grow on me).

and wow, matryoshka! ♥