SCHEDULE 13G/A 0001910313 XXXXXXXX LIVE 4 Class A ordinary shares 09/30/2025 0001758530 So-Young International Inc. 83356Q108 2/F, East Tower, Poly Plaza No. 66 Xiangbin Road, Chaoyang District Beijing F4 100102 Rule 13d-1(d) MPC III L.P. (f/k/a Matrix Partners China III, L.P.) b E9 0 5599035 0 5599035 5599035 N 6.1 PN This statement on Schedule 13G is filed by MPC HK III, MPC III, MPC III-A, MPC Management III, MPC III GP (each as defined in Item 2(a) of the Original Schedule 13G (as defined below)) and David Su ("Su," collectively, with MPC HK III, MPC III, MPC III-A, MPC Management III and MPC III GP, the "Reporting Persons"). The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G. Consists of 1 Class A ordinary share and 7,278,745 ADSs held indirectly by MPC III (through MPC HK III). MPC Management III and MPC III GP are the direct and indirect general partners, respectively, of MPC III and MPC III-A, and as such, may exercise voting and dispositive power over these shares. Su, a director of MPC III GP, may be deemed to share voting and dispositive power over these shares. This percentage is based on a total of 91,126,150 Class A ordinary shares outstanding as of September 30, 2025, as disclosed to the Reporting Persons by the Issuer. MPC III-A L.P. (f/k/a Matrix Partners China III-A, L.P.) b E9 0 622118 0 622118 622118 N 0.7 PN The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G. Consists of 6 Class A ordinary shares and 808,746 ADSs held indirectly by MPC III-A (through MPC HK III). MPC Management III and MPC III GP are the direct and indirect general partners, respectively, of MPC III and MPC III-A, and as such, may exercise voting and dispositive power over these shares. Su, a director of MPC III GP, may be deemed to share voting and dispositive power over these shares. This percentage is based on a total of 91,126,150 Class A ordinary shares outstanding as of September 30, 2025, as disclosed to the Reporting Persons by the Issuer. MPC Management III L.P. (f/k/a Matrix China Management III, L.P.) b E9 0 6221153 0 6221153 6221153 N 6.8 PN The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G. Consists of (i) 1 Class A ordinary share and 7,278,745 ADSs held indirectly by MPC III and (ii) 6 Class A ordinary shares and 808,746 ADSs held indirectly by MPC III-A (in each case through MPC HK III). MPC Management III and MPC III GP are the direct and indirect general partners, respectively, of MPC III and MPC III-A, and as such, may exercise voting and dispositive power over these shares. Su, a director of MPC III GP, may be deemed to share voting and dispositive power over these shares. This percentage is based on a total of 91,126,150 Class A ordinary shares outstanding as of September 30, 2025, as disclosed to the Reporting Persons by the Issuer. MPC GPGP III Ltd. (f/k/a Matrix China III GP GP Ltd.) b E9 0 6221153 0 6221153 6221153 N 6.8 CO The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G. Consists of (i) 1 Class A ordinary share and 7,278,745 ADSs held indirectly by MPC III and (ii) 6 Class A ordinary shares and 808,746 ADSs held indirectly by MPC III-A (in each case through MPC HK III). MPC Management III and MPC III GP are the direct and indirect general partners, respectively, of MPC III and MPC III-A, and as such, may exercise voting and dispositive power over these shares. Su, a director of MPC III GP, may be deemed to share voting and dispositive power over these shares. This percentage is based on a total of 91,126,150 Class A ordinary shares outstanding as of September 30, 2025, as disclosed to the Reporting Persons by the Issuer. MPC III HK Limited (f/k/a Matrix Partners China III Hong Kong Limited) b K3 0 6221153 0 6221153 6221153 N 6.8 CO The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G. Consists of (i) 1 Class A ordinary share and 7,278,745 ADSs held indirectly by MPC III and (ii) 6 Class A ordinary shares and 808,746 ADSs held indirectly by MPC III-A (in each case through MPC HK III). MPC Management III and MPC III GP are the direct and indirect general partners, respectively, of MPC III and MPC III-A, and as such, may exercise voting and dispositive power over these shares. Su, a director of MPC III GP, may be deemed to share voting and dispositive power over these shares. This percentage is based on a total of 91,126,150 Class A ordinary shares outstanding as of September 30, 2025, as disclosed to the Reporting Persons by the Issuer. David Su Tuong Sing b U0 0 6221153 0 6221153 6221153 N 6.8 IN The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G. Consists of (i) 1 Class A ordinary share and 7,278,745 ADSs held indirectly by MPC III and (ii) 6 Class A ordinary shares and 808,746 ADSs held indirectly by MPC III-A (in each case through MPC HK III). MPC Management III and MPC III GP are the direct and indirect general partners, respectively, of MPC III and MPC III-A, and as such, may exercise voting and dispositive power over these shares. Su, a director of MPC III GP, may be deemed to share voting and dispositive power over these shares. This percentage is based on a total of 91,126,150 Class A ordinary shares outstanding as of September 30, 2025, as disclosed to the Reporting Persons by the Issuer. So-Young International Inc. 2/F, East Tower, Poly Plaza, No. 66 Xiangbin Road, Chaoyang District, Beijing, China 100102 This Amendment No. 4 (this "Amendment") amends and supplements the Schedule 13G originally filed by the Reporting Persons with the United States Securities and Exchange Commission (the "Commission") on February 13, 2020, as amended by Amendment No. 1 as filed with the Commission on February 14, 2022, Amendment No. 2 as filed with the Commission on February 9, 2024 and Amendment No. 3 as filed with the Commission on August 14, 2025 (collectively, the "Original Schedule 13G"). Only those items that are hereby reported are amended; all other items reported in the Original Schedule 13G, remain unchanged. Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable. Capitalized terms not defined in this Amendment have the meanings ascribed to them in the Original Schedule 13G. Item 2(b) of the Origininal Schedule 13G is incorporate herein by reference. Item 2(c) of the Origininal Schedule 13G is incorporate herein by reference. Y See Row 9 of the cover page for each Reporting Person and the corresponding comments. See Row 11 of the cover page for each Reporting Person and the corresponding comments. See Row 5 of the cover page for each Reporting Person and the corresponding comments. See Row 6 of the cover page for each Reporting Person and the corresponding comments. See Row 7 of the cover page for each Reporting Person and the corresponding comments. See Row 8 of the cover page for each Reporting Person and the corresponding comments. Y Y Y Y Y Y MPC III L.P. (f/k/a Matrix Partners China III, L.P.) /s/ David Su 10/27/2025 MPC III-A L.P. (f/k/a Matrix Partners China III-A, L.P.) /s/ David Su 10/27/2025 MPC Management III L.P. (f/k/a Matrix China Management III, L.P.) /s/ David Su 10/27/2025 MPC GPGP III Ltd. (f/k/a Matrix China III GP GP Ltd.) /s/ David Su 10/27/2025 MPC III HK Limited (f/k/a Matrix Partners China III Hong Kong Limited) /s/ David Su 10/27/2025 David Su Tuong Sing /s/ David Su 10/27/2025