Form SC 13G/A So-Young International Filed by: Apax Digital L.P.

The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

This CUSIP applies to the American Depositary Shares (“ADSs”), evidenced by American Depositary Receipts. Thirteen ADSs represent ten Class A ordinary shares of the Company.

Names of Reporting Persons

Youthful Acquisition L.P.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Citizenship or Place of Organization

Guernsey

Number of

Shares

Beneficially

Owned by

Each

Reporting Person

With:

Sole Voting Power

0

Shared Voting Power

3,496,015 (1)

Sole Dispositive Power

Shared Dispositive Power

3,496,015 (1)

Aggregate Amount Beneficially Owned by Each Reporting Person

3,496,015 (1)

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (9)

5.1% (2)

Type of Reporting Person (See Instructions)

PN

Represents 4,544,820 ADSs (representing 3,496,015 Class A ordinary shares) held by Youthful Acquisition L.P.

The calculation of the foregoing percentage is based on 68,658,575 Class A ordinary shares of the Company outstanding as of September 30, 2021, as reported in the Company’s Form 6-K filed on November 19, 2021.

Names of Reporting Persons

Youthful GP Co. Limited

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Citizenship or Place of Organization

Guernsey

Number of

Shares

Beneficially

Owned by

Each

Reporting Person

With:

Sole Voting Power

0

Shared Voting Power

3,496,015 (1)

Sole Dispositive Power

Shared Dispositive Power

3,496,015 (1)

Aggregate Amount Beneficially Owned by Each Reporting Person

3,496,015 (1)

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (9)

5.1% (2)

Type of Reporting Person (See Instructions)

OO

Represents 4,544,820 ADSs (representing 3,496,015 Class A ordinary shares) held by Youthful Acquisition L.P.

The calculation of the foregoing percentage is based on 68,658,575 Class A ordinary shares of the Company outstanding as of September 30, 2021, as reported in the Company’s Form 6-K filed on November 19, 2021.

Names of Reporting Persons

Apax Digital L.P.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Citizenship or Place of Organization

Guernsey

Number of

Shares

Beneficially

Owned by

Each

Reporting Person

With:

Sole Voting Power

0

Shared Voting Power

3,496,015 (1)

Sole Dispositive Power

Shared Dispositive Power

3,496,015 (1)

Aggregate Amount Beneficially Owned by Each Reporting Person

3,496,015 (1)

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (9)

5.1% (2)

Type of Reporting Person (See Instructions)

PN

Represents 4,544,820 ADSs (representing 3,496,015 Class A ordinary shares) held by Youthful Acquisition L.P.

The calculation of the foregoing percentage is based on 68,658,575 Class A ordinary shares of the Company outstanding as of September 30, 2021, as reported in the Company’s Form 6-K filed on November 19, 2021.

Names of Reporting Persons

Apax Digital Co-Investment L.P.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Citizenship or Place of Organization

Guernsey

Number of

Shares

Beneficially

Owned by

Each

Reporting Person

With:

Sole Voting Power

0

Shared Voting Power

3,496,015 (1)

Sole Dispositive Power

Shared Dispositive Power

3,496,015 (1)

Aggregate Amount Beneficially Owned by Each Reporting Person

3,496,015 (1)

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (9)

5.1% (2)

Type of Reporting Person (See Instructions)

PN

Represents 4,544,820 ADSs (representing 3,496,015 Class A ordinary shares) held by Youthful Acquisition L.P.

The calculation of the foregoing percentage is based on 68,658,575 Class A ordinary shares of the Company outstanding as of September 30, 2021, as reported in the Company’s Form 6-K filed on November 19, 2021.

Names of Reporting Persons

Apax Digital GP L.P. Inc.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Citizenship or Place of Organization

Guernsey

Number of

Shares

Beneficially

Owned by

Each

Reporting Person

With:

Sole Voting Power

0

Shared Voting Power

3,496,015 (1)

Sole Dispositive Power

Shared Dispositive Power

3,496,015 (1)

Aggregate Amount Beneficially Owned by Each Reporting Person

3,496,015 (1)

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (9)

5.1% (2)

Type of Reporting Person (See Instructions)

PN

Represents 4,544,820 ADSs (representing 3,496,015 Class A ordinary shares) held by Youthful Acquisition L.P.

The calculation of the foregoing percentage is based on 68,658,575 Class A ordinary shares of the Company outstanding as of September 30, 2021, as reported in the Company’s Form 6-K filed on November 19, 2021.

Names of Reporting Persons

Apax Digital GP Co. Limited

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)  ☐        (b)  ☒

SEC Use Only

Citizenship or Place of Organization

Guernsey

Number of

Shares

Beneficially

Owned by

Each

Reporting Person

With:

Sole Voting Power

0

Shared Voting Power

3,496,015 (1)

Sole Dispositive Power

Shared Dispositive Power

3,496,015 (1)

Aggregate Amount Beneficially Owned by Each Reporting Person

3,496,015 (1)

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)

☐

Percent of Class Represented by Amount in Row (9)

5.1% (2)

Type of Reporting Person (See Instructions)

OO

Represents 4,544,820 ADSs (representing 3,496,015 Class A ordinary shares) held by Youthful Acquisition L.P.

The calculation of the foregoing percentage is based on 68,658,575 Class A ordinary shares of the Company outstanding as of September 30, 2021, as reported in the Company’s Form 6-K filed on November 19, 2021.

Name of Issuer:

So-Young International Inc. (the “Company”)

Address of Issuer’s Principal Executive Offices:

Tower E, Ronsin Technology Center

Chaoyang District, Beijing,

People’s Republic of China

Name of Person Filing:

Address of Principal Business Office or, if none, Residence:

Citizenship:

YOUTHFUL ACQUISITION L.P.

P.O. BOX 656

EAST WING, TRAFALGAR COURT, LES BANQUES

ST. PETER PORT, GUERNSEY GY1 3PP

PLACE OF ORGANIZATION: GUERNSEY

YOUTHFUL GP CO. LIMITED

P.O. BOX 656

EAST WING, TRAFALGAR COURT, LES BANQUES

ST. PETER PORT, GUERNSEY GY1 3PP

PLACE OF ORGANIZATION: GUERNSEY

APAX DIGITAL L.P.

3/F, ROYAL BANK PLACE

1 GLATEGNY ESPLANADE

ST. PETER PORT, GUERNSEY GY1 2HJ

PLACE OF ORGANIZATION: GUERNSEY

APAX DIGITAL CO-INVESTMENT L.P.

3/F, ROYAL BANK PLACE

1 GLATEGNY ESPLANADE

ST. PETER PORT, GUERNSEY GY1 2HJ

PLACE OF ORGANIZATION: GUERNSEY

APAX DIGITAL GP L.P. INC.

3/F, ROYAL BANK PLACE

1 GLATEGNY ESPLANADE

ST. PETER PORT, GUERNSEY GY1 2HJ

PLACE OF ORGANIZATION: GUERNSEY

APAX DIGITAL GP CO. LIMITED

3/F, ROYAL BANK PLACE

1 GLATEGNY ESPLANADE

ST. PETER PORT, GUERNSEY GY1 2HJ

PLACE OF ORGANIZATION: GUERNSEY

The foregoing persons are hereinafter collectively referred to as the “Reporting Persons.” Any disclosures herein with respect to persons other than the Reporting Persons are made on information and belief after making inquiry to the appropriate party.

The Class A Shares (as defined below) reported herein are held by Youthful Acquisition L.P. Youthful Acquisition L.P. is majority beneficially owned by Apax Digital L.P. and Apax Digital Co-Investment L.P. Youthful GP Co. Limited is the general partner of Youthful Acquisition L.P. and is wholly owned by Apax Digital L.P. and Apax Digital Co-Investment L.P. Apax Digital GP L.P. Inc. is the general partner of each of Apax Digital L.P. and Apax Digital Co-Investment L.P. Apax Digital GP Co. Limited is the general partner of Apax Digital GP L.P. Inc. and the Investment Manager of Apax Digital L.P. and Apax Digital Co-Investment L.P.

Title and Class of Securities:

Class A ordinary shares, par value $0.0005 per share (“Class A Shares”). Thirteen American depositary shares (“ADSs”) represent ten Class A Shares.

CUSIP No.:

83356Q108

Item 3.   If this statement is filed pursuant to §§240.13d-1(b), or 240.13d-2(b) or (c), check whether the person filing is a:

Not applicable.

Item 4.

Ownership

(a)   Amount beneficially owned:

As of the date hereof each of the Reporting Persons may be deemed to be the beneficial owner of the 4,544,820 ADSs (representing 3,496,015 Class A Shares) held by Youthful Acquisition L.P.

(b)   Percent of class:

See Item 11 of each cover page.

(c)   Number of shares as to which such person has:

(i) Sole power to vote or to direct the vote

See Item 5 of each cover page.

(ii)  Shared power to vote or to direct the vote

See Item 6 of each cover page.

(iii)  Sole power to dispose or to direct the disposition of

See Item 7 of each cover page.

(iv) Shared power to dispose or to direct the disposition of

See Item 8 of each cover page.

Item 5.

Ownership of Five Percent or Less of a Class.

Item 6.

Ownership of More than Five Percent on Behalf of Another Person.

Item 7.

Item 8.

Identification and Classification of Members of the Group.

Item 9.

Notice of Dissolution of Group.

Item 10.

Certifications.

Description