In the Japanese Fan Service anime, I have been watching (High School DXD, Cat Planet Cuties, Valkyrie Drive Mermaid, and the Monogatari series), there exists a time in life between childhood and the rest of life called High School. There is a bubble where all the big decisions and challenges happen, mostly independent of parents and society. The space between being a puppy and dog. Issues of sex, establishment of adult relationships, threats, blessings, hormones, innocence, priorities, amoral drives, principles, passion, and ethics all come up and are dealt with open-eyed.
I had a lot of trouble at first watching these because of the stated or implied age of the characters. I had to give in because like my cultural reality, the high school years depicted (ages 15 to 18) are a bubble. ‘High School’ becomes a literary device where mature (older than 18-year-old individuals) have strictly defined roles and are not part of this temporary first society. Younger individuals’ roles are also strictly limited. Worlds can be created using ‘High School’ as a limiting backdrop that will inevitably reconnect these metamorphosing individuals with the world in a totally different way than when they were a child. Plot elements can be added in the form of something interesting, (ex: aliens, the supernatural, superpowers, a parallel world that others are unaware of…). Fan service in these stories is nudity or sexually charged scenes. Fan service is tied to necessity in Valkyrie Drive Mermaid; male character mind bending hormones in High School DXD; and innocence in Cat Planet Cuties. The fan service like other elements is used to further character development as the story arc continues.
I watch fan service in that occasionally seeing nudity makes anything more bearable and enjoyable for me unless it is criminal, demeaning, abusive, or false. I tend to lose interest in most decent but not great shows quickly. This is partially due to what I feel is a lack of honesty or commitment on their creators and actors’ parts. Not having nudity or sex where they belong can often be as warping as having them where they do not belong. It can be as warping as having characters that are one dimensional and plots that are based on misunderstandings, society norms, prejudices, dehumanizing desires, and false ethics.
There are, of course, Fan Fiction anime I find unwatchable for reasons mentioned earlier. Nudity is not enough. Spices do not a meal make, but it can help what might be a little bit bland otherwise.