An action may be performed now in preparation for a future action. Performing the action now allows for convenience later, such as studying today to do better on a test tomorrow. This is conveyed by taking a verb in its て form and following it with おく.
The て form of a verb, followed by the verb おく or おきます (“put”), expresses an action done deliberately for a future convenience. Here, おく or おきます is used as an auxiliary and is conventionally written in hiragana, not kanji.
Kamiya, Taeko. “Actions: in Progress, Completed, Successive, Simultaneous, and Miscellaneous.” Japanese Sentence Patterns for Effective Communication, Kodansha, 2005, p. 113
Vて + おく “do something in advance”
Vて + おく expresses an action which is performed in advance for future convenience. The verb おく (put) is used as an auxiliary.
Kamiya, Takeo. “Usage of Verb Forms.” The Handbook of Japanese Verbs, Kodansha, 2001, p. 171
N は V おきます。
N does V beforehand.
This pattern provides a means of saying a certain action (て form verb) is done in preparation for an upcoming event: e.g. putting the beer in the refrigerator in preparation for a party, or putting the papers for a meeting on the director’s desk so that he can go over them prior to the meeting. “To do something beforehand” is represented by おきます.
Chino, Naoko. “Basic Pattern 41.” A Dictionary of Basic Japanese Sentence Patterns, Kodansha, 2000, p. 237
Doing Something in Advance
When the て form is followed by the verb おく, the meaning is to do something in advance or as preparation for something else; it can also mean to put away or preserve for later use.
Chino, Naoko. “Expressing Time Relationships.” Japanese Verbs at a Glance, Kodansha, 2000, pp. 95–96
do something in advance for future convenience
おく as a main verb means “put” or “place”. However, when it is used with Vて, it is an auxiliary verb meaning “to do something in advance and leave the resultant state as it is for future convenience”.
With a causative verb, Vて おく can express the idea that someone lets someone or something remain in his / its present state.
Vて おく may be contracted into とく or どく in informal conversation.
Makino, Seiichi and Michio Tsutsui. “Main Entries.” A Dictionary of Basic Japanese Grammar, The Japan Times Ltd., 1989, pp. 357–358
- How to use Vておく ( = te oku) (maggiesensei.com)