Exhibit 5.1

Mayer Brown LLP 71 South Wacker Drive Chicago, Illinois 60606 United States of America   T: +1 312 782 0600 F: +1 312 701 7711 mayerbrown.com

May 7, 2021

Nissan Auto Receivables Company II LLC

One Nissan Way

Franklin, TN 37067

(615) 725-1664

Re: Nissan Auto Receivables Company II LLC

Registration Statement on Form SF-3

(Registration No. 333-[_______])

Ladies and Gentlemen:

We have acted as special counsel to Nissan Auto Receivables Company II LLC, a Delaware limited liability company (the “Company”), in connection with the above-captioned registration statement (such registration statement, together with the exhibits and any amendments thereto, the “Registration Statement”), filed by the Company with the Securities and Exchange Commission in connection with the registration by the Company of Asset Backed Notes (the “Notes”). As described in the Registration Statement, the Notes will be issued from time to time in series, with each series being issued by a statutory trust (each, a “Trust”) to be formed by the Company pursuant to a Trust Agreement (each, a “Trust Agreement”) between the Company and a trustee. For each series, the Notes will be issued pursuant to an Indenture (the “Indenture”) between the related Trust and an indenture trustee (the “Indenture Trustee”).

In that regard, we are generally familiar with the proceedings taken or to be taken in connection with the proposed authorization, issuance and sale of any series of Notes and have examined and relied upon copies of such statutes, documents, corporate records and other instruments as we have deemed necessary or appropriate for the purposes of this opinion, including the Registration Statement and, in each case as filed as an exhibit to the Registration Statement, the form of Underwriting Agreement, the form of Indenture (including the form of Notes included as an exhibit thereto), the form of Amended and Restated Trust Agreement, the form of Purchase Agreement, the form of Sale and Servicing Agreement, the form of Interest Rate Cap Agreement, the form of Asset Representations Review Agreement and the form of Administration Agreement (collectively, the “Operative Documents”). Terms used herein without definition have the meanings given to such terms in the Registration Statement.

Based on and subject to the foregoing, we are of the opinion that, with respect to the Notes, when (a) the related Indenture has been duly qualified under the Trust Indenture Act of 1939, as

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May 7, 2021

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amended, (b) the Notes have been duly executed and issued by the related Trust, authenticated by the Indenture Trustee, and sold by the Company, and (c) payment of the agreed consideration for the Notes has been received by the related Trust all in accordance with the terms and conditions of the related Operative Documents and a definitive purchase, underwriting or similar agreement with respect to such Notes and in the manner described in the Registration Statement, such Notes will have been duly authorized by all necessary action of the related Trust and will be legally issued and binding obligations of the related Trust and entitled to the benefits afforded by the Indenture, except as may be limited by bankruptcy, insolvency, reorganization, arrangement, moratorium or other similar laws relating to or affecting creditors’ rights generally (including, without limitation, fraudulent conveyance laws), and general principles of equity, including without limitation, concepts of materiality, reasonableness, good faith and fair dealing and the possible unavailability of specific performance or injunctive relief, regardless of whether such enforceability is considered in a proceeding in equity or at law.

Our opinions expressed herein are limited to the federal laws of the United States of America, the laws of the State of New York and the Delaware Limited Liability Company Act and the Delaware Statutory Trust Act. We express no opinion herein as to the laws of any other jurisdiction and no opinion regarding the statutes, administrative decisions, rules, regulations or requirements of any county, municipality, subdivision or local authority of any jurisdiction.

We hereby consent to the filing of this opinion with the Securities and Exchange Commission as an exhibit to the Registration Statement and to the use of our name therein without admitting we are “experts” within the meaning of the Securities Act of 1933, as amended, or the rules and regulations of the Securities and Exchange Commission issued thereunder, with respect to any part of the Registration Statement or this exhibit.

Sincerely,

/s/ Mayer Brown LLP

Mayer Brown LLP