v3.26.1
Income taxes - Current and deferred components of income tax expenses, disaggregated by jurisdiction (Details)
 12 Months Ended
Dec. 31, 2025
CNY (¥)
Dec. 31, 2025
USD ($)
Dec. 31, 2024
CNY (¥)
Dec. 31, 2023
CNY (¥)
Current income tax expense:        
Current tax expense, domestic ¥ 24,067,270 $ 3,441,573    
Total current tax expense 30,674,579 4,386,405 ¥ 65,805,623 ¥ 64,458,408
Deferred income tax expense/(benefit)       (2,117,892)
Total income tax expense:        
Income tax expense/(benefit), domestic 24,067,270 3,441,573    
Total income tax expense/(benefit) 30,674,579 4,386,405 ¥ 65,805,623 ¥ 62,340,516
Hong Kong        
Current income tax expense:        
Current tax expense, foreign 5,673,334 811,276    
Total income tax expense:        
Income tax expense/(benefit), foreign 5,673,334 811,276    
United States        
Current income tax expense:        
Current tax expense, foreign 834,699 119,360    
Total income tax expense:        
Income tax expense/(benefit), foreign 834,699 119,360    
Australia        
Current income tax expense:        
Current tax expense, foreign 93,526 13,374    
Total income tax expense:        
Income tax expense/(benefit), foreign 93,526 13,374    
United Kingdom        
Current income tax expense:        
Current tax expense, foreign 5,750 822    
Total income tax expense:        
Income tax expense/(benefit), foreign ¥ 5,750 $ 822