Chisa Kotegawa is the female protagonist and one of the major characters of the manga series Grand Blue. She is a first year Mechanical Engineering student at Izu University. Chisa is initially seen as a level-headed and serious girl who takes her studies seriously. She is rarely seen taking part in Peek-a- Boo's drunken antics, usually sitting off and observing instead. Though this makes her seem cold, she actually avoids such antics because she is extremely weak to alcohol (this may be the normal reaction, as Peek-a-Boo's alcoholic beverages usually have above 90% alcoholic content). She loves diving and is usually the most eager to do any diving related activity. She abhorred the example set by her fellow club members, and was quite hostile when her friends attempt to involve her in their antics. She is incredibly stubborn; once having set her mind on something being almost impossible to convince otherwise. Despite being considered beautiful and getting hit on constantly in her university, Chisa is disinterested in romance. She aspires to be a diving instructor.