Japanese Suru Verbs Guide: Noun Plus Suru, O, Loanwords and Dekiru

The core idea: the noun carries the meaning, suru carries the grammar

Take the noun benkyō, study. It cannot show tense or politeness, because nouns do not conjugate. Now attach suru, the plain verb to do, and you have a full verb: benkyō suru. Think of suru as a handle that fits any tool. The noun is the tool and changes from verb to verb. The handle is always the same one.

Two things follow at once. First, you conjugate only suru, so every suru verb in the language conjugates identically. Second, the noun keeps its own character, including the particles it likes. Denwa, a phone call, goes to someone, so the person takes ni. Sanpo, a walk, moves through a place, so the park takes o. You are telling a new colleague about your week.

Conjugation table: only suru changes

Suru is one of the two irregular verbs of Japanese, but it is irregular in the same way everywhere. Here is benkyō suru in the forms you will need first.

Notice that the stem wanders between shi, su, sa and se. That is the irregular part, and it is worth saying the column aloud until it is automatic. The guides to verb groups and verb conjugation on this blog set suru beside the regular verbs.

With and without o: minimal pairs and the one-o rule

Because the noun is a real noun, it can step away from suru and become its object: benkyō o suru. Literally: do study. The meaning does not change. What changes is the space left in the clause.

A Japanese clause has room for one direct object. In Nihongo o benkyō suru, the whole verb is benkyō suru and its object is Nihongo. If you put o after benkyō, the object slot is taken, and Nihongo has to attach to the noun with no: Nihongo no benkyō o suru. Literally: do the study of Japanese. Two o particles in one clause are not accepted.

The third pair shows why the separated form is useful. Once the noun stands alone, it can take wa, mo or dake, and it can be described: nagai ryokō o shita, I took a long trip. An adjective needs a noun to describe, so nagai ryokō shita, with no particle, is only heard in loose casual speech.

Loanword verbs: kopī suru, kyanseru suru

A Japanese verb has to end in a particular sound and fit a conjugation pattern, which makes foreign verbs hard to import. Nouns have no such requirement. So English verbs enter Japanese as nouns, and suru makes them verbs on the spot: kopī suru, literally do a copy. This is why the family keeps growing.

Be ready for meanings that have narrowed. Sain suru means to sign your name. Kanningu suru means to cheat in an exam. A small number of loanwords take the ending ru directly instead, such as saboru, to skip class or work, and guguru, to search online, but these are informal exceptions. You are at the office, asking a colleague for help before a business trip.

Which nouns can take suru, and which cannot

The handle fits only tools that do something. A noun accepts suru when it names an action, an event or a change: sōji, cleaning, ryokō, travel, shitsumon, a question, seikō, success, anshin, relief. Why not the others? Suru means do, and you cannot do a desk.

Three groups catch learners. Objects and places never take suru. Nouns for something you have use ga aru: kyōmi ga aru, to be interested, ninki ga aru, to be popular. Na-adjectives such as genki and shizuka describe states and take da. Shizuka ni suru exists, but it means to make something quiet, which is a different pattern.

In the other direction, suru is more generous than the word noun suggests. Many sound-symbolic words and adverbs take it and become verbs of feeling or manner. A friend is describing the moment before a job interview, and then a lazy weekend.

Beyond the basics: dekiru, nasaru and itasu

If suru is a handle, it can be swapped for a different handle without touching the noun. Three swaps matter. Dekiru is the potential: yoyaku dekiru, can reserve. Nasaru is the honorific, used for the actions of someone you respect, and its polite form is the slightly irregular nasaimasu. Itasu is the humble form, used for your own actions towards someone you respect.

You will hear nasaru and itasu from staff long before you need to produce them. For your own speech, learn o-negai itashimasu first. For honorific suru verbs, many speakers choose the passive-shaped sareru, as in shusseki saremasu ka, will you attend, which is lighter than nasaru. The scenes: a customer on a booking site, a waiter, a receptionist, the end of an email.

Beyond the basics: one-kanji suru verbs such as aisuru and sassuru

A small group of verbs is written with a single kanji plus suru: aisuru, to love, sassuru, to sense or guess, yakusuru, to translate. Here the core idea fits less well, and it is better to admit it. The first part is not an independent noun in the same way, and the two parts cannot be separated: ai o suru is wrong.

Their conjugation is also less tidy. Aisuru has forms that behave like an ordinary godan verb, so its negative is aisanai and its potential is aiseru, while aishimasu and aishite look like suru. Yakusuru is often simply yakusu. Treat each of these as a separate vocabulary item and check a dictionary for its forms.

Neighbours and spoken reality: yaru, naru and what gets dropped

Suru has two neighbours. Yaru is a rougher, more casual do. It can replace suru when the noun stands apart as an object, shukudai o yaru, but it cannot be attached directly: benkyō yaru is not said. Naru, to become, is the mirror image of suru. Chūshi ni suru means somebody cancels the event, and chūshi ni naru means the event ends up cancelled, with nobody named. Separate posts on this blog cover both pairs.

In conversation, o between the noun and suru is dropped more often than it is kept, and shite iru shrinks to shiteru. In messages and headlines even suru can vanish, leaving the noun to stand for the whole verb.

Common mistakes with suru verbs

The first mistake is the double o: Nihongo o benkyō o shimasu is wrong. Learners know both patterns and blend them. Choose one: Nihongo o benkyō shimasu, or Nihongo no benkyō o shimasu.

The second is copying English particles. Tomodachi o denwa shimashita and kare o kekkon shimashita are wrong, because in English you call someone and marry someone. In Japanese the noun decides: a call goes to a person, tomodachi ni denwa shimashita, and a marriage is with a person, kare to kekkon shimashita.

The third is inventing a potential from suru: benkyō sureru and benkyō shirareru are wrong. Learners apply the regular potential rules to an irregular verb. The potential is a different handle altogether: benkyō dekiru.

The fourth is adding suru to nouns that do not name actions: kyōmi suru and genki suru are wrong. English has verbs such as interest, so the gap is not obvious. Say kyōmi ga aru and genki da.