Satsuki Tsukino

"Taking care of and teaching their stupid younger siblings is a Older sister's duty!"

- Satsuki Tsukino Satsuki Tsukino(月野五月; Tsukino Satsuki), is the eldest daughter of the Tsukino Household and a supporting character in Highschool DxD: Яe-birth, being also the main antagonist of Yoko's side through volume 8. She's a doctor of Kuoh city clinics, a former student of Kuoh academy and Ichijou Tsukino eldest half-sister.

Due to her name, she's usually referred as "Gou-nee"(ゴウ姉; "Go-nee") by her younger siblings and friends.

Appearance
Satsuki is a beautiful young lady onm her early twenties with chesnut-colored hair which she usually combs in a high-ponytail, fair skin, grey eyes and a mature, tall body structure. According to Kyou, Satsuki probably inherited mostly of her appearance from her father Hajime.

Being a doctor at Kuoh cosmetics and hospital, she's usually seem with a labcoat either before leaving or at home, and have a like for dark clothes. She appears also to be a tall lady since she tops all of her siblings and even Kyou for a few centimeters.

Personality
The eldest of the Tsukino siblings, Satsuki seems to be the most mature and responsible of the five, with the possible and close exception of her youngest Ichijou. She's down-to-earth, patient and homely however also showing a more passive-agrassive and violent side due to her non-nonsensical mentality, shown when she nonchalantly elbowed Shion for a joke and beats the rest of them on the regular basis. Just like the other sisters, she has the habit of bullying Ichijou in order to "tough him up", and despite this, deeply loves and cares for him.Being the eldest of the bunch, she also seems to lead the family when either her parents are away.

Just like Ichijou, Satsuki seems to have a certain ease in attracting people from the opposite sex, since she claims she had several boyfriends and the nasty habit of breaking up with them. Also, according to Ichijou, she's the only other sibling who can cook and sew, abilities he learnt from.

History
Satsuki is the eldest and first daughter of Hajime Tsukino and a nameless woman. Born from his first marriage, Satsuki would never meet her real mother after she leaves Hajime for cheating on her, the lover also leaving him with her own daughter she had with him, who would grow up to be Shion.

After another failed marriage and another half-sibloing, Minatsu, Hajime would finnaly settles with Kyou and have with her Futaba and Ichijou. Being the eldest daughter, Satsuki would take care and discipline her younger siblings, and, after discovering what happened between Ichijou and the twins Nina and Julia, she commanded the others to start scaring him in order to respect women, so that he wouldn't end up like their father and make others suffer like she did.

Powers & Abilities
Unhuman Strength - Trained on the arts of self-defense from her father and mother and having to take care of her younger siblings, Satsuki developed an unhuman strength that can easily surpass and subdue her siblings, and powered-Ichijou included, with relatively ease, her punches being strong enough to cause shockwaves and create small tornadoes. She also seems to have immense endurance, as a punch from Nemesis Gremory during the school festival didn't faze her in the slightlest.

Unhman Speed - She also developed this technique after years balancing college, her duty as the eldest sister and her personall life. She's fast enough to catch all of her fleeing siblings and be one of the first to finish her laps during the school festival. Satsuki is also fast enough to hit Kurama, a sage, before she can even react to.

Martial Arts master - Satsuki is well-versed in self-defense and martial arts, being a master in savate and Blackbelt in karate. She also seems to like wrestling and sumo a lot, since she usually locks and drops various techniques on her siblings.;

Trivia

 * Satsuki's images are based on the character Chisa Yukizome from the DanganRonpa series.
 * Just like her other siblings, she's named after a number. In her case, her name literally has the ideogram for the number five("五"; Gou); being the eldest sibling of five, her whole name standing for may, and also can be read as "52".
 * Satsuki's name is a pun with "Tsuki No Satsu"(月の 冊), which can be read "Moon's booklet", a reference with ichijou's name, which means "One article/page".
 * Satsuki's the only sister who calls Ichijou harem members by tbeir nicknames.