Japanese particles を, に, で and へ

を: the object

is said o. It marks the object: the thing an action is done to, like the coffee in “I drink coffee”. It comes straight after the object, before the verb: (kōhī o nomimasu, I drink coffee). You also use it when you ask for something: (mizu o kudasai, some water, please).

With verbs of movement, marks the place you go through, along or out of: (kōen o arukimasu, I walk through the park), (densha o orimasu, I get off the train).

水をください。Mizu o kudasai.Some water, please.
毎朝新聞を読みます。Maiasa shinbun o yomimasu.I read the newspaper every morning.
次の駅で電車を降ります。Tsugi no eki de densha o orimasu.I get off the train at the next station.

に: a point in time

(ni) marks an exact point in time: a clock time, a day of the week, a date, a month or a year. (shichiji ni okimasu) means “I get up at seven”.

Words that are relative to today, such as (kyō, today), (ashita, tomorrow), (maiasa, every morning) and (raishū, next week), don't take (ni). With (shūmatsu, the weekend) and parts of the day you can use it or leave it out.

With (ni)	Without (ni)
(shichiji ni) at seven o'clock	(kyō) today
(getsuyōbi ni) on Monday	(ashita) tomorrow
(itsuka ni) on the fifth	(maiasa) every morning
(sangatsu ni) in March	(raishū) next week
(nisen nijūnen ni) in 2020	(kyonen) last year

毎朝七時に起きます。Maiasa shichiji ni okimasu.I get up at seven every morning.
月曜日に会議があります。Getsuyōbi ni kaigi ga arimasu.There's a meeting on Monday.
明日、友達に会います。Ashita, tomodachi ni aimasu.I'm meeting a friend tomorrow.

に: where something is, and where you go

With (arimasu) and (imasu), marks where something or someone is: (Ginkō wa eki no mae ni arimasu, the bank is in front of the station). It also marks where you live: (Kyōto ni sunde imasu, I live in Kyoto).

With verbs of movement such as (ikimasu, go), (kimasu, come) and (kaerimasu, go home), marks the destination. It also marks the person you meet, phone or give something to, and what you get on: (basu ni norimasu, I get on the bus).

銀行は駅の前にあります。Ginkō wa eki no mae ni arimasu.The bank is in front of the station.
明日京都に行きます。Ashita Kyōto ni ikimasu.I'm going to Kyoto tomorrow.
毎晩母に電話します。Maiban haha ni denwa shimasu.I phone my mother every evening.

で: where an action happens, and how

(de) marks the place where an action happens: (toshokan de benkyō shimasu, I study at the library). Compare with (imasu): (toshokan ni imasu, I'm at the library). (ni) is where you are, (de) is where you do something.

also marks the means, the tool or the language you use: (densha de ikimasu, I go by train), (hashi de tabemasu, I eat with chopsticks), (Nihongo de hanashimasu, I speak in Japanese). In shops, (zenbu de) means “all together”.

Particle	Question it answers	Example
(ni)	where is it?	(eki ni imasu) I'm at the station.
(de)	where does it happen?	(eki de machimasu) I'll wait at the station.
(de)	how, with what?	(basu de ikimasu) I'll go by bus.

駅で友達を待ちます。Eki de tomodachi o machimasu.I'll wait for my friend at the station.
毎日バスで会社に行きます。Mainichi basu de kaisha ni ikimasu.I go to work by bus every day.
日本語で話しましょう。Nihongo de hanashimashō.Let's speak in Japanese.

へ: towards

is written with the sign for he but said e. It marks the direction of movement, “towards”. With , and it means almost the same as : puts a little more weight on the direction, and it sounds slightly more written.

One difference: can be followed by (no) to describe a noun, and can't: (haha e no tegami, a letter to my mother). You'll also see it in (Nihon e yōkoso, welcome to Japan).

来週大阪へ行きます。Raishū Ōsaka e ikimasu.I'm going to Osaka next week.
何時に家へ帰りますか。Nanji ni ie e kaerimasu ka.What time are you going home?
日本へようこそ。Nihon e yōkoso.Welcome to Japan.