mermaid's hands got dark because he want to get out from that garden, the reason he wants to get out is shinobu has sex with a man, and he wants to stop them. But he fail to get out.
shinobu used that sword 'cause at the beginning he was a teacher for that mermaid, but his time duration of teaching him already end. n the mermaid's power isn't complete, and he needs to kill him but he can't. He just injured mermaid's right eye.
the 3rd question.. i don't know how to answer it.. I've never heard and read 'bout the 'mermaid picked up Norio'
*Sorry for my bad English.. still learning (● ̄(エ) ̄●)
Oh thanks alot dear Kurokawa, im really really greatful to u. And ur english is way better than mine :-) And in last volume marmaid goes to Norio and take him to his place, Shinobu is there too. Story is not finished yet , but I don't know what he says to Norio. What he want from him,
http://www.77mh.com/201505/313136.html?page=48
Here is the link
Guys do u know why marmaid hands got dark? And why shinobu used that sword on marmaid? And why marmaid picked up norio?