Actually, the "loli" at the top (Sarisa) is the only NPC crucial to the plot. Everybody else on the cover represents one of the game's 14 character classes.
I did a quick translation of the official character summaries from the manual, if anyone's interested. The manual lists six of the game's important NPCs. There are more, but I'm leaving out spoilers here. For reference, characters are listed in the order they appear on the
official character summary page. "CV" stands for "character voice," i.e. the voice actor playing that character. I've left those untranslated because it's a pain in the * and who the hell cares.
(Note: For some reason, the official website lists some Newman characters' race as "??," while the manual just says "Newman." Their bigass ears are a dead giveaway, so I'm siding with the manual on this one. Also, just because the Japanese site uses messed up Romanizations does NOT mean that those are the "correct" names, but I'm including those along with more likely localizations.)
Sarisa
Age: 14
Race: Newman
A Newman girl. With her meek personality, Sarisa's emotions are very easy to read. She's an avid reader, full of curiosity. As soon as she came down to Earth, she gazed in awe at the beautiful landscapes surrounding her.
Quote: "I'm on the surface... I've truly arrived!"
Kai
Age: 22
Race: Human
A veteran hunter and strong leader, Kai is not one to fuss over small details, preferring instead to simply get the job done.
Quote: "In this dangerous age, it's important never to leave a debt unpaid."
Ogi
Age: Unknown
Race: Android
An android belonging to the Hunter's Guild. He is investigating the mysterious circumstances of his lost past. While usually serious, Ogi sometimes surprises the party with his odd manner of speaking.
Quote: "The pursuit of my hidden past... it seems I'm the only one who doesn't exist."
Reve (possibly Leve or Leive/Reive)
Age: 20
Race: Newman
A Newman elite, she is the commander of the landing team. She despises humans and androids, and is known to be quite full of herself.
Quote: "...Those contemptible humans never show up when support is needed."
Ana
Age: 20
Race: ??
From her appearance, you might guess that she's a Newman. However, Ana's true origin remains shrouded in mystery. She is waiting for the right moment to reveal her true appearance...
Quote: "Greetings, people of the surface. I must apologize for inviting you here on such short notice."
Dairon (possibly Dylon/Dyron/Dylone/Dyrone)
Age: 46
Race: Human
Mayor of Dairon city and a representative of the Hunter's Guild. He has a reputation as a playful, suave gentlemen, but is becoming concerned about his thinning hair.
Quote: "By my authority, I hereby recognize you as full-fledged Hunters!"