Shirai Ageha (白井 揚羽), also known as Yoshino (吉野), is a character in Ryū ga Gotoku Kenzan!
Ageha was born in the town of Kiryu in Kozuke Province; the eldest daughter of a mildly famous samurai named Shirai Seinoshin. She lived a normal life working on her family's farm alongside her father and her younger sister, Ukiyo, until one day during her late teens when her father was challenged to a duel by a samurai called Majima Gorohachi. Seinoshin was killed in the subsequent duel and the girls were left to bear their father's debts, eventually having to sell the farm to pay them off.
Ageha and Ukiyo left Kozuke and headed to Kyoto to try and find work in the booming city economy. Together, they managed to scrounge up a meagre living, barely getting paid enough to survive by doing menial work. Eventually, Ageha grew tired of seeing her sister suffer, so she sold herself to Tsuruya; a brothel in Kyoto's pleasure district of Gion, and gave Ukiyo the money so she could start a new life elsewhere. Despite initially being hesitant to leave her sister behind, Ageha insisted that Ukiyo leave the city and live free of worry. Ukiyo ended up buying a farm in Omi Province and kept in contact with her sister through letters. Via their letter-writing, Ageha learned that her sister eventually met Majima Gorohachi once again while he traveled through Omi and the men was so contrite over the death of their father that he decided to move to Ukiyo's village and protect her farm from bandits to make amends.
In Kyoto, Ageha took on the pseudonym of "Yoshino" and dedicated herself to her new life as a courtesan. She practiced playing the shamisen, singing, dancing and did everything she could to please her customers. She grew incredibly popular and within only a couple of years of moving into Gion, she'd become the most beloved and successful courtesan in the district.
In 1601, while Yoshino was still rising through the ranks of Tsuruya's courtesans, she met Miyamoto Musashi (who went by the alias of Kiryu Kazumanosuke) when he and a wandering monk hired her services. Unbeknownst to her, Miyamoto had until recently been Ukiyo's lover and hired her because of their resemblance (though Miyamoto was not aware of the relationship between Ukiyo and Yoshino). While the pair talk at the brothel, the two quickly connect but are interrupted when an angry patron causes a scene in the adjacent room. While Miyamoto deals with the rowdy customer at the manager's behest, he leaves his sword with Yoshino and she recognizes a charm which Ukiyo had previously tied around its hilt. Despite this, the pair continue seeing each other after Kiryu moves into Gion and they quickly become close.
However, months later, word reaches Yoshino that Ukiyo had been killed in her village, supposedly by a man named Miyamoto Musashi. Due to the presence of the charm around the sword's hilt, Yoshino comes to suspect that Kiryu was Miyamoto, but she did not pursue the suspicion further out of fear that the man she'd become so close with was her sister's killer.
In 1605, a 10 year-old girl called Haruka sells herself to Tsuruya so she can afford to pay Kiryu to hunt down her family's killer: a man named "Miyamoto Musashi". Kiryu takes on the job out of admiration for the girl's determination and to catch the imposter killing people while pretending to be him. As Haruka now had to become an apprentice in Yoshino's brothel, Kiryu asked the courtesan to look after the girl while she was there, since he felt responsible for her. Over the next few weeks, Yoshino would mentor Haruka in how to work as an assistant at Tsuruya and she quickly grew fond of the girl, as she reminded her or herself when she was starting out. She would also defend Haruka when older girls start to bully her, much to Kiryu's gratitude.
A few months later, a feast is to be held at Tsuruya to honor Itakura Katsuhige's five years as Governor of Kyoto. The day prior to the feast, Yoshino is approached by Sasaki Kojiro and offered a deal: He wants her to sneak off during the feast and start a fire, which will serve as a distraction for his assassination of Itakura. In exchange, Sasaki offers her 500 ryo: Enough money to buy her freedom. Though at first hesitant to collaborate with a murder, Yoshino agrees. Unbeknownst to her, on top of murdering Itakura, Sasaki also intends to kill Haruka.
During the feast, Yoshino entertains Itakura for a time, until she receives a covert signal from Sasaki to begin their plan. She sneaks off to the courtesans quarters and sets the fire as instructed; causing enough chaos for Sasaki and his men to murder Itakura and get away. Fortunately, however, Sasaki's co-conspirator Marume Nagayoshi did not wish to go through with murdering a child, so he allowed Haruka to escape.
- Yoshino is loosely based on a fictional character of the same name from Eiji Yoshikawa's novel, Miyamoto Musashi. In the novel, Yoshino is a courtesan from Gion who falls in love with Miyamoto Musashi while he stays in town to duel the masters of the Yoshioka Dojo. However, unlike in Kenzan!, Yoshino's affection is not reciprocated by Miyamoto.