It turned out that one of the Hourai's gem branches had been kept inside the enclosed space in an ink brush painting belonging to Nuinoin and his wife. With Byakuya's help, Aoi enters the world of the ink brush painting with Ginji, Ranmaru, and Chibi.
What you were seeking is 
right in front of you.
Merkst du nicht, dass das,
was wir suchen, vor uns ist?