Convertible bonds (Details) |
Jun. 30, 2026
USD ($)
|
Jun. 30, 2026
CNY (¥)
|
Dec. 31, 2025
CNY (¥)
|
|---|---|---|---|
| Defined Benefit Plan Disclosure [Line Items] | |||
| Total bonds payable | $ 6,440,000 | ¥ 43,862,196 | |
| Investor [Member] | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Total bonds payable | $ 6,440,000 | ¥ 43,862,196 | ¥ 45,265,472 |