"Tell Me"

Appearance wise, Tsukiumi has long blonde hair and blue eyes. She is dressed in a black dress with a white underdress which shows her cleavage, a black and white choker, and long brown boots with black stockings. Because of her short skirt her panties are often exposed which led to her being given the nickname "Panties Flasher" by Homura and Kazehana. She wears a light blue nightgown when she going to bed. At Izumo Inn she is often dressed in a maid outfit she got from Uzume to do chores.

Personality wise, Tsukiumi is a Sekirei with a prominent tsundere personality. She is the most aggressive of Minato's party and has a very short temper; she rarely smiles. She was introduced as the first Sekirei that wanted to become the strongest without the help of an Ashikabi. She even stated that she was willing to kill her future Ashikabi if she would ever react to him/her, due to her hate towards Ashikabi.[4] She changed a great deal after getting winged by Minato and easily gets jealous when Minato comes in contact with other women, due to her feelings for her Ashikabi. She proclaims herself to be Minato's only legal wife which sometimes causes confrontations between her and Minato's other Sekirei. She often competes with Musubi, attempting to gain the sole right to be called 'Minato's legal wife'. This is because she stated after kissing Minato for the first time that he was not only her Ashikabi but her husband. Aside from this, she gets along well with Minato's other Sekirei; especially those she considers her direct rivals, Homura and Musubi.

She also has an honorable side, in that she seems to adhere to the fundamental rule of Sekirei one-on-one combat. Tsukiumi also seems to despise involving innocent civilians or bystanders in such confrontations, as seen when she canceled her attack on the veiled Uzume when Kazehana came by (Tsukiumi was unaware that Kazehana was Sekirei Number 3 at the time). Furthermore, she has a tendency to show a softer nature around Minato and has stated in a private conversation with Miya that she wants to become the strongest in order to stay with Minato forever.

Tsukiumi doesn't like to be touched by anyone except Minato. She gets mad when Musubi grabs her breast in the bath or while undressed. Minato is the only one allowed to touch her body and once she went so far as to place Minato's hand to her exposed breast; even so, shortly afterward she considered this a "brief moment of weakness."

Tsukiumi's most notable character trait is her pride. She sometimes undertakes actions she knows are foolish simply because her pride won't let her back down. Fortunately it is a trait she is learning to overcome, such as when Kusano managed to convince her to help #95 Kuno and her Ashikabi escape even though it went against Tsukiumi's principles.

Her speech pattern is different from others, as she speaks in the Old Japanese Language. (To reflect this in the English dub, she speaks in Shakespearean English using words such as "Thou" or "Thee" in place of typical pronouns.)

In the epilogue (Sekirei: 365 Days Without Her), she expresses a desire to bear Minato's children after learning about Hibiki and Hikari's pregnancies from Miyajima, however, her prideful attitude prevents her from directly admitting this.