Koto ga Aru: Talking About Your Experiences in Japanese

What koto is doing in the sentence

Koto packages a verb phrase into a noun so the rest of the sentence can talk about it. Nihon ni iku means go to Japan; nihon ni iku koto means the act of going to Japan, and once it is a noun it can be the thing that exists, the thing you can do, or the thing you decided. Every pattern in this guide is that one move followed by an ordinary verb, which is why they all end in arimasu, dekimasu, shimasu, or narimasu.

That is also why the patterns feel long. Japanese does not add a special ending for experience or ability; it makes a noun and then says the noun exists or is possible. If you keep that image, you will attach the right ending without memorising four unrelated shapes, and you will hear the pattern coming in someone else's speech as soon as koto arrives.

The koto patterns at a glance

Only the first row uses the past form of the verb. Everything else attaches to the plain dictionary form, so the visible difference between have done it and it sometimes happens is a single syllable. Say the two example sentences back to back a few times until the ta in the first one stands out to your own ear.

Building the experience form from the dictionary form

The experience pattern needs the plain past, the ta form. If you already know the te form, swap the final e for a, since the sound changes are identical: nonde becomes nonda, itte becomes itta, tabete becomes tabeta. Ichidan verbs simply drop ru and add ta. The two irregulars are suru to shita and kuru to kita, which is read kita with a short i.

Experience, not a dated event

This is the rule that decides whether a sentence sounds native. Ta koto ga aru counts something into your life history: you have climbed Mount Fuji, you have eaten nattō, you have been to a Japanese wedding. It cannot report a single event pinned to a time. As soon as you say kinō, senshū, or san-ji ni, the sentence has to become the plain polite past.

The same restriction blocks things everyone does routinely. Gohan o tabeta koto ga arimasu sounds absurd because eating is not a rare achievement. Use the pattern where the answer might genuinely be no, and use the past tense for what happened on a particular day.

A useful test before you speak: could you follow the sentence with itsu desu ka and expect an answer? If yes, you are describing an event, so use the past tense. If the natural follow-up is nan-kai desu ka, how many times, you are describing experience and koto ga arimasu is right.

Dictionary form plus koto ga aru for what sometimes happens

Keep the verb in the dictionary form and the same ending stops meaning experience and starts meaning frequency. Densha ga okureru koto ga arimasu tells your colleague that trains are late from time to time, not that a train was once late. Adverbs such as tama ni, toki doki, and mare ni sit naturally in front of it, and a plain negative works too: tabenai koto ga arimasu, there are times I do not eat.

Koto ga dekiru beside the potential form

Koto ga dekiru turns the verb into a noun and says it is possible. The potential form does the same job inside the verb itself: hanasu becomes hanaseru, yomu becomes yomeru, taberu becomes taberareru, kuru becomes korareru, and suru simply becomes dekiru. Both are correct, so the choice is about register. The long form sounds more formal and explicit, which suits notices, rules, and careful explanations; the potential form is shorter and dominates ordinary speech.

One detail matters when you swap them. Koto ga dekiru keeps the object marked with o, because the object still belongs to the inner verb: nihongo o hanasu koto ga dekimasu. The potential form usually takes ga instead: nihongo ga hanasemasu. Mixing the two, as in nihongo ga hanasu koto ga dekimasu, is the mistake to watch for.

If you want one rule for speaking: use the potential form with friends and colleagues, and reach for koto ga dekimasu when you are explaining a rule, reading a sign back, or answering an interviewer who asked what you are able to do.

Koto ni suru for your decision

Koto ni suru presents a choice you made. The past koto ni shimashita is the usual conversational form, since you normally report a decision after making it. The negative attaches to the plain negative verb, not to shimasu: ikanai koto ni shimashita, I decided not to go. There is also a continuous koto ni shite imasu, which describes a rule you have set yourself and still keep, and it is the neatest way to talk about a habit you chose on purpose.

Koto ni naru when the decision arrives

Koto ni naru says the matter has become settled, without pointing at who settled it. Companies use it for transfers, offices for schedules, and people use it for news that grew out of circumstances rather than a single choice. Koto ni narimashita is how most such announcements are phrased. The continuous koto ni natte imasu describes a standing rule, which is why house rules and workplace procedures often end that way.

Compare the pair directly. Yameru koto ni shimashita says I decided to quit; yameru koto ni narimashita says it has been arranged that I will leave. The first takes responsibility, the second reports an outcome, and in a workplace the second is often the kinder thing to say.

Negatives and questions you will actually use

The negative of the experience pattern changes arimasu, not the verb: itta koto ga arimasen. Add ichido mo for never at all, and mada for not yet, which quietly leaves the door open. Questions are formed with ka in the usual way, and nan-kai gives you the follow-up that keeps the conversation moving.

A full experience exchange

Asking about experience is one of the safest small-talk moves in Japanese, because it invites a story rather than an opinion. The pattern to copy is simple: ask with ka, answer with a count, then add a detail in the plain past. A bare hai kills the conversation, so the second sentence is the part that matters.

Notice the last line. Turning the question back with sochira wa dō desu ka or the more casual A-san wa costs one breath and doubles the length of the conversation. Prepare one experience answer with a detail attached and you will never be stranded at a bare yes.

Mistakes to fix before your next conversation

• Do not attach a date to the experience pattern; kinō, senshū, and a clock time all force the plain polite past instead.
• Do not use it for everyday actions such as eating or sleeping, where the answer could never be no.
• Keep the ta form correct: itta not ikita, nonda not nomita, kita for kuru and shita for suru.
• Negate arimasu, not the verb, so it is tabeta koto ga arimasen rather than tabenakatta koto ga arimasu.
• With koto ga dekiru, leave the object marked with o and save ga for the potential form.
• Choose koto ni shimashita for a choice you made and koto ni narimashita for an outcome that was settled around you.