Aburako Dousan

About
Oily Girl Dousan might be a minor character in Sengoku Rance without many appearances or even unique affection events, but she is well loved for the ability to recruit her early in a run through, and her extraordinary skills in battle, most notably her proficiency in Action Transfer, which allows her to replenish allies both in troop and solo battles, unlike many other monks, who only have the skill available in solo battle.

Personality and Appearance
Based on an April Fool's joke (see trivia), she naturally has a humorous and bubbly personality. In battle, she will shout lines like "Maximum slippery!" or "I think I can submerge myself in this!".

Oily Girl, despite appearing to be a cute girl, is actually a youkai and the daughter of the 'oil presser' or Abura-sumashi, a youkai in Japanese folklore who would steel oil from travellers. You might also notice her unique battle text where she hesitantly stutters when deployed in battle against Masamune in battle, or her line "I-I live freely!", when battling Omachi, a reference to the Great Youkai War.

The line she shouts in the MangaGamer version of Sengoku Rance "I'm the oil-dwelling girl, Oily Girl, sliding onto the scene!" is actually a mistranslation... The 'Abura sumashi 油すまし' in her battle speech '油すましの娘、油娘！ぬるっと行くよー. ' is actually a reference to her dad. Funnily enough, it's translated accurately in the non-official translation by Takajun, "I'm Aburako, daughter of Aburasumashi! Let's be oily!". (It's possible it's meant as a pun, as abura sumashi is a homonym for 'oil-dweller', and her scuba gear)

Despite her youkai origins, Oily Girl is a noble in Mino in her original setting, with human subordinates, including the Mino Triumvirate, Stubborn Ittetsu, Cucumber Andou, and Takuan-sama, commanders who can be recruited after conquering the Mamushi Oil province, and who 3G holds in high regard.

In another event involving the triumvirate, the three discuss whether or not to accept Ashikaga Choushin's request that they fight for him. Of note, Cucumber reflects on how he loves eating cucumber with the greasy food that Oily Girl Dousan used to make before she disappeared, abandoning Mino because of Choushin's banishment of the Saitou Clan just before the events of Sengoku Rance.

Saitou Dousan is likely her adopted father considering the shared family name and the fact that Dousan is stated to have disappeared from Mino at the same time that Choushin banished Saitou. She is also closely linked to Saitou, the historical figure, who was an oil merchant turned feudal lord. This makes her somewhat unique as a kind of heir of the Saitou Clan, and a noble in human society, despite being a youkai by birth.

The meaning of "Oily" should not, however, be taken solely as a reference to greasy food. From her lines, we can safely interpret the Oily in her name to have a double reference to grease, as well as to petrol, as she talks about how she is an oil dweller and wears scuba gear in her depictions.

The idea of oil spills is definitely expressed both in her scuba gear as well as her original reference in a game about an adventure at sea (see trivia).

Trivia

 * Saitō Dōsan is the name of a Japanese Daimyo (feudal lord) who was Nobunaga's father in law (the father of Chou). Dousan was also known as the Viper of Mamumushi. Dousan was originally became a monk, before turning to selling oil (for cooking) and later developing political and military power and becoming a Daimyo.
 * Oily Girl Dousan was originally announced as the main character of "Oily Girl's Heart-Pounding Adventure At Sea" (油娘どきどき海中旅行), an April Fool's game announcement by Alice Soft in 2005.