N.D. Cent. Code § 15-08-15

The fee of each parcel of land sold on contract must remain in the state until a patent or deed is issued therefor as provided in this title. After a failure on the part of the purchaser, or the purchaser's heirs or assigns, to comply with the terms of the contract or with the provisions of law applicable thereto, any person being or continuing in possession of any such lands without the written permission of the commissioner must be deemed to detain the land forcibly and without right and to be a trespasser thereon.