v3.26.1
Income taxes - Reconciliation of taxes at the PRC statutory rate to our provision for income taxes (Details)
12 Months Ended
Dec. 31, 2025
CNY (¥)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
CNY (¥)
Dec. 31, 2023
CNY (¥)
Income taxes        
Net income before income taxes ¥ 739,301,975 $ 105,718,775 ¥ 157,537,018 ¥ 101,474,055
Effective Income Tax Rate Reconciliation, Amount        
Income tax expense at PRC statutory income tax rate 184,825,494   39,384,255 25,368,514
Tax exempted income     113,208,078 198,231
Changes in valuation allowance     (249,072,857) (91,301,461)
Total income tax expense/(benefit) ¥ 30,674,579 $ 4,386,405 ¥ 65,805,623 ¥ 62,340,516
Tax Jurisdiction of Domicile [Extensible Enumeration] PRC PRC    
Effective Income Tax Rate Reconciliation, Percent        
Income/(loss) before income tax 100.00% 100.00%    
Statutory income tax rate 25.00% 25.00% 25.00% 25.00%
Effective tax rate 4.10% 4.10% 41.80% 61.40%
PRC        
Effective Income Tax Rate Reconciliation, Amount        
Tax exempted income ¥ (10,955,971)      
Write-off of NOL 22,301,473      
Changes in valuation allowance (112,048,066)      
Other ¥ 7,315,121      
Effective Income Tax Rate Reconciliation, Percent        
Tax exempted income (1.50%) (1.50%)    
Write-off of NOL 3.00% 3.00%    
Changes in valuation allowance (15.20%) (15.20%)    
Other 1.00% 1.00%    
Hong Kong        
Effective Income Tax Rate Reconciliation, Amount        
Tax exempted income ¥ (1,966,394)      
Changes in valuation allowance 22,856,618      
Other 5,632,510      
Statutory tax rate difference ¥ 10,150,643      
Effective Income Tax Rate Reconciliation, Percent        
Tax exempted income (0.30%) (0.30%)    
Changes in valuation allowance 3.10% 3.10%    
Other 0.80% 0.80%    
Statutory tax rate difference 1.40% 1.40%    
Cayman        
Effective Income Tax Rate Reconciliation, Amount        
Statutory tax rate difference ¥ (104,556,655)      
Effective Income Tax Rate Reconciliation, Percent        
Statutory tax rate difference (14.10%) (14.10%)    
Other foreign jurisdictions        
Effective Income Tax Rate Reconciliation, Amount        
Other ¥ 7,119,806      
Effective Income Tax Rate Reconciliation, Percent        
Other 1.00% 1.00%