In short

Hang いく or くる on a て-form and the action gets a direction relative to you: 持っていきます motte ikimasu (“I’ll take it - away from here”) versus 持ってきます motte kimasu (“I’ll bring it - here”). The same pair also works on the time axis: 〜てきました is a change that has run from the past up to now (寒くなってきました samuku natte kimashita, “it has been getting cold”), and 〜ていきます is a change carrying on from now into the future (増えていきます fuete ikimasu, “it will keep increasing”).

The rule

Step 1 - Build it, and only move the tail. The pattern is V-て + いく and V-て + くる. The て-form is frozen; every tense, politeness and negative marker sits on the last word. As auxiliaries these two are normally written in kana (持っていく, 帰ってくる), even though the standalone verbs are 行く and 来る - kana is the safe default.

食べる taberu -> 食べて -> 食べていきます tabete ikimasu 買う kau -> 買って -> 買ってきます katte kimasu

くる keeps all the irregularity of 来る: きます／きた／こない／きてください. Learners hear this shift long before they can see it, because the kana hides the reading.

Step 2 - Space: find the deictic centre. The “centre” is wherever the speaker is standing, or mentally standing - normally here and now, sometimes home, sometimes the place being described in a story.

• 〜ていく = the action proceeds away from that centre. 歩いていきます aruite ikimasu (“go there on foot”), 出ていきました dete ikimashita (“walked out”), 帰っていった kaette itta (“went off home”, seen from where I stayed).
• 〜てくる = the action proceeds toward it. 走ってきました hashitte kimashita (“came running”), 入ってきます haitte kimasu (“comes in”), 帰ってきます kaette kimasu (“comes back”).

With a carrying verb this is exactly English “take” versus “bring”: 持っていく motte iku / 持ってくる motte kuru for objects, 連れていく tsurete iku / 連れてくる tsurete kuru for people and animals. Use 持つ for what fits in your hands and 連れる for anyone who walks.

Step 3 - The go-and-come-back 〜てくる. With a verb that is not itself motion, 〜てくる very often means “go, do it, and come back” - the round trip is the point.

• 買ってきます katte kimasu - “I’ll go and buy it (and be back)”
• 取ってきます totte kimasu - “I’ll go and fetch it”
• ちょっと行ってきます chotto itte kimasu - “I’m just popping out”

This is why leaving the house you say 行ってきます itte kimasu, literally “I go and come back” - never 行きます, which sounds like you are not returning. The household exchange is fixed: 行ってきます -> いってらっしゃい itterasshai, and on return ただいま tadaima -> お帰りなさい okaerinasai. Learn all four as one set.

Step 4 - Time: which way does the change run? Here the “movement” is along the calendar, and the deictic centre is now.

• 〜てきた／〜てきました - the change started in the past and has arrived at the present. 寒くなってきました, 増えてきました fuete kimashita, 分かってきました wakatte kimashita (“I’m starting to get it”). Because the change has to reach now, this use most often appears in the past form - a non-past 寒くなってくる (“it’ll be turning cold”) is possible, just much less common.
• 〜ていく／〜ていきます - the change leaves now and continues forward. 増えていきます, 忘れていくでしょう wasurete iku deshō (“we’ll go on forgetting”), 生きていきます ikite ikimasu (“I’ll go on living”), やっていきます yatte ikimasu (“I’ll manage”). This use is usually non-past; a past 増えていった narrates a trend running on from some earlier point in the story.

The verbs that take the temporal reading are the ones that name a gradual change: なる, 増える, 減る, 変わる, 分かる, 慣れる. Pair 〜てくる with これまで kore made (“up to now”) and 〜ていく with これから kore kara (“from now on”) and the two stop blurring.

Step 5 - Emergence and perception take 〜てくる. When something comes into view, into earshot or into existence, it is arriving at you, so くる is the only option:

見えてきました miete kimashita (“it came into sight”), 聞こえてきました kikoete kimashita (“it became audible”), 雨が降ってきました ame ga futte kimashita (“it started raining”), 眠くなってきました nemuku natte kimashita (“I’m getting sleepy”). There is no ×見えていく for this - nothing is receding from you.

Step 6 - Stacking with 〜ている. 〜てきている is normal and useful: 人口が増えてきています jinkō ga fuete kite imasu, “the population has been rising (and still is)”. 〜ていっている does occur (増えていっている is attested), but it is much rarer and you rarely need it. The lopsidedness is not arbitrary: 〜ている wants a change that has already produced a state holding now, and てくる has just delivered exactly such a state; ていく points away from now, so there is much less for ている to hold on to. For the future, plain 増えていきます is the natural choice.

Step 7 - This is not the same as 〜始める／〜続ける. Those attach to the ます-stem and describe a phase of the event itself - lexical aspect. 〜ていく／〜てくる attach to the て-form and describe the event’s relation to your standpoint - deixis. 降り始めました furihajimemashita is a neutral report that the rain began; 降ってきました puts you under it, noticing it now. The full compound-verb family is Compound verbs.

Forms & patterns

Only the auxiliary conjugates. Stem verb: 持つ motsu (“carry”).

Spatial pairs: away from me / toward me.

Temporal: which side of “now”.

Deictic (this lesson) versus lexical (compound verbs). Same verb 増える fueru (“increase”).

Examples

Common mistakes

• 明日、公園にカメラを持ってきます。 (Ashita, kōen ni kamera o motte kimasu.) -> 明日、公園にカメラを持っていきます。 (Ashita, kōen ni kamera o motte ikimasu.) - The park is not where you are standing as you speak, so the camera travels away from you: いく. てくる would mean carrying it to your own location.
• 寒くなっていきました。 (Samuku natte ikimashita.) -> 寒くなってきました。 (Samuku natte kimashita.) - A change that ran from the past up to the present arrives at now, so it takes てくる, and normally in the past form. ていく points the other way, out of now into the future.
• 人口が増えていっています。 (Jinkō ga fuete itte imasu.) -> 人口が増えてきています。 (Jinkō ga fuete kite imasu.) - For a trend that has run up to the present, the anchor is now and the view is backwards, so てくる is the one you want; 〜ていっている exists but is much rarer and points the other way. For the future, say plain 人口が増えていきます.
• 友達を持ってきます。 (Tomodachi o motte kimasu.) -> 友達を連れてきます。 (Tomodachi o tsurete kimasu.) - 持つ is for objects you carry in your hands. Anyone who walks in on their own legs - people, pets - takes 連れる.
• 今日はお弁当を持ってきないでください。 (Kyō wa obentō o motte kinaide kudasai.) -> 今日はお弁当を持ってこないでください。 (Kyō wa obentō o motte konaide kudasai.) - The auxiliary is 来る, so it is き in きます／きて but こ in こない. Written in kana the change of reading is invisible; drill it aloud.

Tips

• Draw the arrow, then read the sentence. くる is an arrow landing on you; いく is an arrow leaving you. That single picture covers both axes: in space the arrow ends at your feet or at the horizon, in time it lands on now (寒くなってきた) or departs from now (寒くなっていく).
• English “bring” is a false friend. English also lets you take the listener’s location as the centre: “I’ll bring wine to your party.” Japanese does not - the centre is where you are. Invited to someone’s place, you say ワインを持っていきます (Wain o motte ikimasu), with いく, because the wine is going away from you.
• 行ってきます is a promise, not a farewell. It literally means “I’ll go and come back”, which is why it is the fixed thing to say on leaving home or the office - and why 行きます in that slot sounds faintly like you are not coming back. Bank the whole exchange: 行ってきます・いってらっしゃい・ただいま・お帰りなさい.
• Learn the fixed collocations as vocabulary. 持っていく／持ってくる, 連れていく／連れてくる, 買ってくる, 取ってくる, 帰ってくる, 出ていく, 見えてくる, 聞こえてくる, 生きていく, やっていく. These come up constantly, and half the battle is that most of them have a one-word English equivalent that hides the structure.