| Schedule of prepaid expenses and other current assets, net |
| | | | | | | | | As of December 31, | | | 2024 | | 2025 | | | RMB | | RMB | | US$ | Deductible input VAT | | 1,444,655 | | 1,814,249 | | 258,945 | Prepaid rental and deposits | | 224,007 | | 332,643 | | 47,478 | Prepayments for materials and advertising fees | | 127,157 | | 124,360 | | 17,750 | Prepaid operating expenses | | 85,212 | | 117,418 | | 16,759 | Interest receivables | | 19,589 | | 84,481 | | 12,058 | Others | | 37,434 | | 47,506 | | 6,780 | | | | | | | | | | 1,938,054 | | 2,520,657 | | 359,770 |
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