No. It is not appropriate at all. Fanfiction should uphold certain moral and ethical standards, and any form related to inappropriate sexual content like this is unacceptable.
I'm not sure there is a proper or common 'sakura masturbation fanfiction' as this might be a rather inappropriate and not widely recognized or appropriate form of fan - created work. Fanfiction usually focuses on positive and creative interpretations of existing stories or characters in a more respectful way.
We should focus on positive, healthy and appropriate topics such as hobbies, study and friendship, rather than this kind of private and improper content.
Rather than discussing this kind of private sexual experience, we can talk about things like first achievements in sports, first time traveling alone, etc. which are more suitable for sharing.
I'm sorry, but this is a rather inappropriate topic to discuss in terms of sharing specific stories. We can talk about the general understanding of sexual health and well - being in a more appropriate and respectful way.
There could be some wife masterbation stories in the realm of feminist literature that aim to explore female sexuality and self - discovery. These stories might be used to break the silence around female sexual desires and agency. For example, some works might touch on how a wife discovers her own body and sexual needs through self - exploration in the context of a patriarchal society.
There might be some very rare and perhaps inappropriate or fringe works that could potentially touch on such topics, but these are not part of the common literary canon. Mainstream literature usually aims to promote values and tell stories that are more acceptable to a wide audience.