What is the name of this manga with a girl pretending to be a mermaid? So a couple years ago I was read this manga, then I finished, because it was an incomplete series, but then I lost it. 

Basically, what I remember is that there was this girl who wanted to join the army after she finished school to help support her mother, and she meets this very weird girl who thinks she is a mermaid and constantly drinks water out of a huge bottle. The girl has weird marks and bruises on her skin, but she brushes is off as "mermaid burns" or something else. 

Then, a celebrity comes to the town, who was super famous and the army girl liked him a little bit. Some stuff happens, and then in the end, it turns out that the celebrity was the "mermaid girls" father and he was abusing her. The series finished after that. 

Please help, it was a very sad manga!
The manga you are looking for is:
Satou Kashi no Dangan wa Uchinukenai 
(Sugar Candy Bullets Can’t Pierce Anything).



The following summaries are included on the website:


  When a strange new girl by the name of Umino Mokuzu transfers in from
  Tokyo and declares that she is a "Mermaid", she quickly becomes the
  center of attention. Noticing that Nagisa is the only classmate that
  seems to have no interest in her, Umino quickly decides that they
  should become "precious friends". Despite Nagisa's objections, Umino
  begins to follow her wherever she goes.


and


  Umino's rockstar father is shown to be aloof towards her at best and
  emotionally abusive at worst, once leaving her behind in a grocery
  store parking lot simply because a defective shopping cart made him
  angry and that's only the tip of the iceberg.