Property and Equipment, Net (Details) - JPY (¥) ¥ in Thousands	6 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Property and Equipment, Net [Abstract]
Depreciation expenses	¥ 99	¥ 99

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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Name:	us-gaap_Depreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration