SCP-5XXX "Abisunohausu"
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Item #: SCP-5XXX Level 3/5XXX
Object Class: Safe Classified


(Fig. 1.1) A series of crude effigies recovered from GoI-078 following the second initiation of Procedure/XXXX-HAGONDE by SCP-XXXX-α's development team.

Special Containment Procedures:

Through limited collaboration with GoI-078 ("Arcadia"), all copies of Stray Back When have been successfully recovered by Foundation personnel. These copies, henceforth designated SCP-XXXX-1, have been stored in a standard containment vault in Site-26. Access to SCP-XXXX-1 by individuals uninvolved with the execution of Procedure/XXXX-HAGONDE is prohibited.

As of 1999-02-29, only one individual associated with the Stray Back When development team remains unaccounted for. Upon their entry into Foundation custody, they are to assist in the initiation of Procedure/XXXX-HAGONDE. Once full containment of SCP-XXXX has been reached, this individual is to be humanely terminated to prevent resurgent anomalous behavior.


SCP-5XXX is an abandoned mansion located in the outskirts of Akita, Japan, that exhibits an extremely high level of Caulli particulates in and around the surrounding area. SCP-5XXX contains three floors, a large attic area, and a multi-level basement. Items interacted with in SCP-5XXX-1 will briefly appear within SCP-5XXX. If these items are not displaced within approximately five minutes, they will demanifest. It is unclear whether SCP-5XXX or SCP-5XXX-1 was created first; government files suggest that SCP-5XXX originally belonged to the Yamadani family, but was transferred to the authorities after World War 2. However, the validity of these files are under review.

SCP-5XXX-1 is the designation for the 1993 videogame Stray Back When. Copies of SCP-5XXX-1 also exhibit high Caulli activity (equiavlent to approx. 300+ ppm3). SCP-5XXX is prominently featured in SCP-5XXX-1; the level design of 5XXX within 5XXX-1 is accurate to SCP-5XXX's floorplans. SCP-5XXX-1 was created by Arcadia Production Team IV1, consisting of:

  • Rebecca Conocco (artist)
  • Peter Solenski (sound and level design)
  • Furutachi Taniyama (writer)
  • George Behling (editor)
  • Adrian Nourent (technical director)

While the members of PTIV show no obvious anomalous properties, their involvement in the creation of SCP-5XXX-1 has established PTIV as anomalous by proxy. Furutachi Taniyama is the only member currently not in Foundation custody.


Logo for SCP-5XXX-1.

Item History:


Furutachi Taniyama.

SCP-5XXX-1 was discovered on August 10th, 1993, after a copy was mailed to Site-126 by an anonymous source named "D.D." Although initial testing determined that its extreme difficulty did not constitute anomalous properties, a more thorough baseline check involving Kant counters flagged SCP-5XXX-1 for anomalously high Hume levels. Several store-bought copies also exhibited the same properties. Foundation implants then proceeded to pull SCP-5XXX-1 instances from retail stores; all SCP-5XXX-1 instances were successfully collected with limited assistance from Arcadia. Documents from PT4 have been provided to the Foundation as well (see Addendum 01).

SCP-5XXX was discovered less than a month following the disappearance of Furutachi Taniyama from covert Foundation surveillance. A temporary investigation was conducted to reascertain the location of Taniyama for immediate detainment by MTF Mu-9 ("Null Squad"). The results of the investigation led to the discovery of SCP-5XXX.

Taniyama's car was found parked outside of SCP-5XXX along with traces of SCP-5XXX having been recently entered. The first iteration of Procedure/5XXX-HAGONDE was executed shortly thereafter.

Addendum 01: Related 5XXX/5XXX-1 Files

Addendum 02: HAGONDE & Subsequent Iterations