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Natsu no Kagerou (なつのかげろう Heat Haze Summer) was a planned video game collaboration between Ryukishi07 and Twilight Frontier. A demo was released, but a complete version never came out.


The end of summer vacation.

The protagonist Kousuke has returned to his hometown of Miwata Village for the first time in three years.

The sky is a clear blue. The clouds are boiling. The sounds of the locusts are noisy.

In the unchanged scenery of the village, Kousuke is reunited with the girls he's known since childhood.

Set in a mountain village in the middle of summer, what will Kousuke find in his interactions with the girls he grew up with?

(Translated from the story page on the official website.)

Development History

The game was first announced on Twilight Frontier's official website on April 1, 2010. Ryukishi and Twilight Frontier had previously collaborated on the 3D fighting game Higurashi Daybreak. According to Ryukishi's production diary post on April 2, 2010, he was first told about Natsu no Kagerou after the completion of Daybreak and started working on it. He was asked to make a horror game similar to Siren.[1]

The scenario for the game was written by G. O. of the doujin company Blank Note, known for creating Himawari. According to his own production diary post on April 3, 2010, G. O. was given the project by Ryukishi.

A demo of the game was released, but for unknown reasons a complete version never came out. The game is still listed on Twilight Frontier's list of products, but with an unknown product number.

Ryukishi's later manga Hotarubi no Tomoru Koro ni is considered a revival of Natsu no Kagerou.[1]


Natsu no Kagerou is advertised as an adventure horror open-world game. The player takes control of Kousuke and can travel around Miwata Village and play with his friends or do other things, spanning the course of four days.

In the demo this was limited to the first day, the player going through several cutscenes and minigames with limited areas to go to as Kousuke plays games with the three girls. The player will only be able to explore the village after gaining control of Kousuke at night and escaping the house. Dying at this stage will send Kousuke back to the checkpoint of fighting his reanimated aunt, making exploration of the dangerous village possibly tedious. Kousuke can only go to the school where Sae is; if the player goes to where either Youko or Wakana are said to be on the map, they'll simply find a locked door.

When the player has control of Kousuke, up to 4 weapons (each having its own durability) can be picked up and swapped between, along with a punch attack and, with a running start, an effective if difficult to aim jumping kick. Kousuke could also sprint but this could force him to stop and catch his breath, and seemed to play a part in the game's unseen health (damage) system.

Combat was quite rough, with attacks sometimes not connecting and stun locks being quite common and often the only way feasible way Kousuke could win fights. Some mouryou, depending on their weapons, are capable of killing Kousuke in one attack or stun lock him to death. As mouryou would reanimate within 20 seconds (outside of the house at the start), coupled with the difficulty of acquiring a decent weapon, combat is best avoided.


Plot Summary

Kousuke returns to his hometown of Miwata Village, greeting the three heroines and playing some interactive minigames with them before having dinner with his relatives. During dinner it is mentioned that Miwata has a tradition of a "mouryou chase" where villagers are chased by "mouryou" but tell him not to worry about it.

Kousuke wakes up after hearing loud sounds at night, and discovers his two adult relatives covered in blood and sporting maniacal smiles. They proceed to attack him, and he is forced to either defend himself or flee. After escaping the house he discovers that the village has been plunged into fog with the now-undead inhabitants of the village wandering about, killing any of the living they find.

Kousuke can only go to the school to advance the story, upon which he finds Sae and some of the surviving villagers taking shelter. While talking with Sae in a classroom a shotgun blast is heard, the two of them discovering that the survivor who greeted them has been killed and reanimated along with the rest of the survivors present. Waiting for the shotgun-wielding now-mouryou to make one of his periodic announcements taunting the pair over the school P.A. and stealing his set of keys, Kousuke and Sae escape the school. Sae mentions a ritual and a well at a nearby graveyard, suggesting they go there; Kousuke obliges. At the graveyard is a gate leading underground; the pair enter and the demo ends.

External Links


  • The possessed villagers (mouryou) bear a strong resemblance to the Shibito from Siren, being partially-intelligent undead that can speak as well as use weapons including firearms; have pale skin and are often covered in blood; constantly smile or grin in a maniacal manner; and if killed will resurrect shortly after. While shibito will in fact regenerate, mouryou will reanimate shortly after following a wind-like sound. Also like shibito, anyone killed by a mouryou by any means (including gunfire) is reanimated as mouryou themselves.