Maru is a character in the anime movie Keroro Gunso the Super Movie 2: The Deep Sea Princess!. She is a Maronian and the right-hand of Meru.
Maru first appeared alongside Meru, when they defeated the Kiruru. She appeared in front of Natsumi after they brought her to Meru. Meru scolded her about blocking his way, at which Maru bowed, apologising.
Maru appears to be more kind-hearted and highly respective of Meru, since she helped to protect him and his love of Natsumi, disallowing Keroro and the others from taking Natsumi back. In one scene, Natsumi asked why Maru wasn't the princess since she was Meru's childhood friend. Maru said that's just what the prince thinks.
It is revealed that they do not even know her own species, since she was shocked when Keroro mentioned that she is a Maronian. After realizing this, Maru turned to support Keroro and the others a bit, opening the door to Meru for them. When Meru turned even larger, she floated in place, shocked, so she changed her mind to stop Meru instead and defended Fuyuki and others from getting killed instantly by Meru's arm cannon, saying Natsumi has her precious family.
Maru is a simply dark blue Maronian. Her crest on her head is shorter and longer ear-like flaps on her helmet. Like Meru, her symbol is a Maron emblem on her forehead and another one on her dress but its colored pink instead of yellow, and has shark-like fins on her wrists and limbs. Her skirt is jagged, and sky blue that matches the same color of her face and belly and orange lines on the lower part of the skirt. Maru's eyes, are larger and rounder shape like a teardrop. Her irises are similar to Meru's and Alisa Southerncross's and its colored magenta.
Maru is kind-hearted and loyal, but often gets trouble so easily when Meru scolds at her. Much like to Natsumi's attitude, she calls Keroro, stupid frog when she gets distracted, cause her to throw a tantrum as she orders her guards to attack him. Her personality changes into a serious and confident nature when it comes in battling.
Maru was initially the second-hand to Prince Meru in the deep sea.
Maru is a very skilled fighter and a swordsman as was shown when she single-handedly defeated Giroro.
Meru - He is Maru's childhood friend and they use to be together as always before arriving in Pekopon. When Meru yelled for help, Maru flew right in and was sucked in. She managed to hold his hand, as he was slowly turned back to his original form surround in red aura with the Mare Ball in his hands.
Natsumi Hinata - She helps Meru to become Natsumi to be his princess but later it didn't turn out to be she was expecting.
Keroro - After Keroro returned to Natsumi's castle, Maru is annoyed to see him again, calling him stupid frog, just like Natsumi calling him.