Natsu Iwashimizu

Natsu Iwashimizu (岩清水 ナツ Iwashimizu Natsu) is the main protagonist of Team Summer B's arc in the 7SEEDS series.

Appearance
Natsu has been noted for being an attractive small girl who has childish features by several members of her team that she has the appearance of a 14 years old with straight neck-length that has square bangs hanging above her eyebrows (her hair eventually grows out), light brown eyes and she is relatively short in stature.

Personality & Characteristics
Natsu is a painfully shy, awkward and withdrawn 16-year-old girl who has difficulty expressing herself that she was always bullied in school. Some scenes depict her as being something akin to a hikikomori, locking herself in her room and feeling bitterness towards those who enjoyed their youth and the society of others.

Although she originally struggles to adapt to the New World, she eventually becomes an asset to the group through her observational and note-taking skills. She diligently names and notes down which foods are edible or useful as her team discovers them.

Over the course of the series, her self-esteem starts to raise and she learns how to better interact with those around her. Semimaru Asai and another certain person, both in their own ways, eventually become mentors to Natsu, teaching her how to overcome her weaknesses and be of more use to those around her.

She is also shy, timid and awkward when interacting with others that she tends not to speak her mind much, but she overthinks things all the time. Originally was incapable of thinking for herself and taking action, something which was scorned by Botan Saotome early on. Often takes the path of least resistance, and what she feels others would want her to do. Has been shown to act kind and considerate around Arashi Aota in order to gain his approval (though this has been called out several times by Semimaru). The manga has depicted her as being inwardly selfish or thinking ill of others several times, however this is also often noticed by Semimaru.

Her personality gradually changes for the better as the manga progresses, with character development being a running theme throughout the series. She is very determined to improve (something noted by Hotaru Kusakuri), and eventually becomes more responsible and learns to think for herself and act accordingly. Arashi points out that Natsu is a tenacious person who doesn't just sit down and cry. He also notes that she is a very careful person who will not do anything without thinking it through thoroughly first.

She also learns to be more conscientious, and her timid yet hard-working personality is acknowledged by Ango, who originally sees her as a replacement for his dead friend, Shigeru, but eventually accepts her as a person in her own right.

Etymology

 * The name Natsu means "summer".
 * Natsu's surname Iwashimizu means "rock" (岩) (iwa), "clear, pure, clean" (清) (shi) and "water" (水) (mizu), which literally means "water trickling from rocks" altogether.