| Character Information
Mars (マルス Marusu) is the second youngest of the Jupiter Sisters and is the fourth goddess revealed. She currently resides within Yui Goidō.
Mars has a rough, perpetually battle-ready personality that also borders on masculinity. She has a habit of using certain rude phrases that are not often heard from females. Being "a warrior who battles evil", she becomes very cautious when entering any unknown situations, as illustrated by her suggestion to Yui that she bring a weapon to her date with Keima, just to be safe. Due to her slight masculine nature — further promoted by her thirst for battle — Mars understands very little in the matters of romance. However, she has been shown to be quite flirtatious. Just like her sisters, Mars cares a great deal about her host, even going as far as taking control in times of danger. Although, because of her ignorance regarding romance, her attempts to make Keima love Yui are far from being romantic.
Mars' true appearance has not been revealed. Whenever she takes control of Yui, Yui's hair is held together in a single braid and acquires a blond color. A white head band also appears on her head and her eyes turn red. Similar to her sisters, she also has a halo on her head and a pair of wings at her back, completing the transformation.
Mars' strength has yet to be measured, but she is shown to be extremely powerful whenever she is in control of Yui. Mars is also a master fencer, and at one point (during Yui's date with Keima) wields a rapier to tear apart opponents' clothing without injuring them.
Yui's relationship with Mars is similar to the relationships between the other goddesses and their respective hosts. They get along very well, even if Mars constantly mistakes Yui for a boy (if her constant mistake is deliberate or not isn't known). Mars will protect Yui from all danger not only because Yui is her host, but also because Yui is her dear friend.
The relationship between Mars and her sisters can be considered normal. They bicker and tease each other, but their love for each other is apparent.