Prepayment and other current assets (Details)	Jun. 30, 2026 USD ($)	Jun. 30, 2026 CNY (¥)	Dec. 31, 2025 CNY (¥)
Prepayment And Other Current Assets
Prepayments	$ 999,340	¥ 6,806,409	¥ 8,514,583
Other receivables	258,959	1,763,742	1,503,790
Less: impairment losses			(2,050,000)
Prepayment and other current assets	$ 1,258,299	¥ 8,570,151	¥ 7,968,373

Amount due from parties in nontrade transactions, classified as other.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 49
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04(5)(a)(5))
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant