Your judgementality towards someone who is likely much more familiar with suicide than you (based off the way you phrased your first comment) is easily 10x more distasteful than someone using fantasy manga nonsense as metaphorical tools in their fictional story about cheery magical girls fighting off the causes of suicide.
Who the fuck else is going to write a story about people fighting off the causes of suicide? Someone from a country with a low suicide rate?
"Oh no, that's terrible. Someone from Japan is metaphorically exploring a huge problem in Japan. It better not have any funny business going on. Only serious business allowed."
And no, you are not "above" anyone here lmao.
Suicide Girl is a very fun story, as you say, in that it really isn't that deep of a manga, so there's really not much metaphorical exploration going on in there. Suicidal behavior not being a naturally-occurring part of human behavior just a big cringy aspect of the setting that you kind of just have to ignore to enjoy the rest.
That was the basic, self-evident kind of observation I'd hoped never to have to explain in so many words, but I suppose the internet just is that full of people whose ability to comprehend and analyze what they're reading is, in fact, far beneath mine, and need these things to be meticulously spelled out. Congratulations on being one of them; maybe you'll get it now. You're quite welcome.
As a sidenote, the author's nationality is entirely irrelevant to this evaluation, as the idea of being Japanese giving you more insight into the subject of suicide is as ridiculous as the idea of you being able to determine the familiarity of strangers on the internet with any given topic based on less than a handful of single-sentence throwaway posts.
Your post, on the other hand, is composed of nothing but formal and informal fallacies, and you should reconsider before you lash out and embarrass yourself like this in the future. Good day.