Forbidden Siren Wiki
Hisako Yao

比沙子 八尾

Hisako yao.jpg
Vital statistics
Title Hisako Yao
Sumiko (澄子; 1976)
Guide Hisako (2003)
Gender Female
Nationality Japanese
Age 1329+ years old (physically 20s)
Abilities Immortality, pyrokinesis, mind manipulation, sightjacking
Weapon None
Allies Datatsushi, Kei Makino, Jun Kajiro, Ayako Kajiro
Voiced by Risako Minami (南りさこ)

Hisako Yao (八尾比沙子) is the main antagonist in Forbidden Siren.

Once a villager of Hanuda in 684 AD, she was cursed by Datatsushi into immortality.


Previous to 1976[]

Hisako was originally a villager of Hanuda in 684 AD. She was the one who discovered Datatsushi's corpse during the great famine of the time. Along with two unnamed villagers, she initiates the devouring of the alien's corpse.

From this, Datatsushi emanates an intense scream (what would be known as the Siren). Hisako appeared visibly shaken by the experience while the others merely covered their ears. Subsequently, she was cursed with immortality unless Datatsushi is summoned back to life.

During the next hundred years she lost her memory, her descendants (The Kajiro family) became the most important family in the village and she will found the Mana Religion.

Hisako Yao eating from Datatsushi

Datatsushi screaming and killing everyone except a pregnant Hisako Yao.

Item 49 - 1.jpg

Item 1.jpg
Item 1 - 2.jpg

Item 26; History of the Kajiro family

Probably during the early 1500's Hanuda's cult was influenced by western religions and began to imitate the Holy Communion using the flesh of a strange being; becomic increasingly esoteric. Later during the first years of the Tokugawa shogunate, the religious prosecution caused the cult to become secret; is at this time that the Homuranagi was created, in order to protect the cult from the shogunate.

After the Meiji restoration, in 1873 with the religious freedom the cult was revived under the guise of the forbidden religion; and around 1900 European missionaries are taken in by the village and find a half fish half person mummy with a strange head.

Item 96; About the history of the Homuranagi.

Item 58

Idol found in a well

The "Baby on the Chopping Board" legend mentions the taboo of eating something that should never be eaten, symbolising something quite characteristic. The "half human half fish" mummy impaled on the plank clearly reflects the memories of Datatsushi, being eaten alive, on a piece of wood that used to be a Mana cross. However, what the idol is actually doing at the bottom of the well is never really explained in-game. Perhaps due to the "original sin" of eating the flesh of the god (Datatsushi) long, long ago, which will never be forgotten, someone left the idol there. 

During the incident of 1976[]

During the 1970's she passed as the maid of the Kajiro family (her descendants) called Sumiko. She helped the Miyako Kajiro of 1976 escape with her lover Takafumi Shimura (Akira Shimura's son); she confined both in the Miyata clinic along with the Uryen.

The ritual failed and a part of the village (The Gojaku peak, Miyata's clinic, the Tabori settlement, Arato, Harayadori and Hirunotsuka) was sent into another dimension. The priest in charge of the ceremony, Reiji Makino commited suicide and a newborn (Kei Makino) was taken in order to fulfill that role in the future, they waited until both the new priest and Miyako Kajiro were ready to conduct the ritual once again.

Takafumi Shimura, locked in a container in the Miyata clinic.

Miyako in the Miyata Clinic in 2003

Item 77, Hisako in clinic.jpg

Item 2; (1976) 33 People missing.

Item 83 (1976 / 7 / 27); Kajiro maid's diary.

During the incident of 2003[]

In 2003, at the beginning of the game, Hisako partakes a sacrificial ritual that was meant to summon Datatsushi. Kyoya Suda's sudden appearance interrupts the ritual and the Siren causes the dead villagers to rise as Shibito.

Item 3; Letter from the Kajiro family to Kei.

Hisako conforts Kei before the ritual.

The ritual being conducted (The day before; 23:11; 2003 / 8 / 1)

She encounters Kyoya Suda in Arato and helps him. Together, they head to the Irazu Valley Church near Karuwari. In Irazu Valley Church, at 7:00 they arrive, but Kyoya goes out shortly after in order to help someone who screamed.

Hisako escorting Kyoya in Arato (Day 1; 2:28)

Kei Makino finds Hisako's veil in Arato

Kyoya with Hisako in the Church, before Kyoya hearing a noise and going to investigate. (Day 1; 7:13)

There she looked at the list of the church members; as she does so her mind becomes foggy. Tomoko Maeda's parents go to the church looking for her, then she leaves the church in search for Tomoko, eventually finding her.

Item 24.jpg

Tomoko's parents arrive to the church looking for Tomoko; (Day 1; 7:38)

Tomoko finds Hisako just after seeing Akira's corpse (Day 1; 21:27)

By 0:00, on the way to the church, she began feeling strange as if someone called her, and ordered Tomoko to enter an abandoned house filled with Shibito; then she vanished alone, switching between multiple personalities, acting as though confused, wandering about, over and over.

At 6:00, self descends in the Utsubobune, picking up the holy vessel that washes up on the shore containing Datatsushi's head, from this point onward, Hisako gains insight into her true purpose. Then by 10:00, with the help of Jun Kajiro, Hisako kidnaps Miyako and starts building a nest around the mirror pool (the source of the red water) to receive her god. The ritual is conducted successfully, summoning a premature form of Datatsushi.

Hisako Yao receives the head of Datatsushi in Harayadori (Day 2; 6:44)

Hisako preparing the sacrfice of Miyako (Day 2; 19:02)

Datatshushi after it's resurection (Day 3; 00:00)

Hisako demands Kyoya to see the Uryen moments before a flood caused by Shiro Miyata separates them (Day 3; 18:09)

But Shiro Miyata destroys the dam and the river floods the nest; the light from the sun causes Datatsushi to burn and die again, then Hisako entered Datatsushi's dimension in order to revive him once again, along with Jun Kajiro who by now was a shibito.

Hisako and Datatsushi in Inferno, before Datatsushi recovers. (Day 3; 23:03)

Hisako suddenly turns old

Hisako, with Datatsushi's head on her arms, fall intro the ground.

Kyoya fights Datatsushi and eventually decapitates it, causing her immortality and youthful appearance to be reversed. She picks up Datatsushi's head and ages rapidly before falling into a dimensional vortex, traveling through time. She gives her younger self the alien god's head, resulting in Datasushi's return.


Hisako up close


As Hisako the Guiding Nun, as Sumiko, the maid of the previous generation Miyako, she is originally a stoutly devoted woman full of affection, and her "selves" bear no ill intentions. However, the awakened Hisako, Yao Bikuni, wishes for her own resurrection as a part of Datatsushi. Her penance, having lasted more than one thousand years, seems to be drawing to an end...


Hisako was a nun of the local Mana religion. She wore a crimson robe with salmon pink accents. She also wore the traditional Mana Cross around her neck.

Initially, her hair was kept tied into a bun, but when she became aware of her true purpose, she let her hair flow freely.

Hisako Facial Animation

Hisako's death animation

Risako Minami


  • 030 - Legend of Yaobikuni.jpg
    Her name, Yao Hisako (尾 · 沙子) is both a reference to the Yao Bikuni (百 · 丘尼)​​:​ Changing 百 for the homophone 尾, and 丘尼 for 沙子. And to the actress that portrayed her (Risako 梨沙子).
  • The (hisa) part of her name can also be the Nanori reading (how characters used for personal names are read) of the character (寿), meaning Longevity or Long life.