We’re looking into this grammar.

Basically, it’s just this format:

Pre-ます(masu) + に(ni) + verb of motion

Examples of verbs of motion are (and the most basic ones):

行く (iku) - to go

来る (kuru) - to come

帰る (kaeru) - to return home

This sentence pattern can be translated as “to go/come (in order) to [verb]”

Examples:

1. 食べに来た。= I’ve come to eat. -Convert 食べる to its pre-ます: 食べる –> 食べ -Add the particle に (which in this usage is like the English “to” or “in order to”. -Then, add your verb of motion. In this case, it’s 来た (kita) “came”, the past tense of 来る (kuru) “to come”. -食べ+に+来た。=  食べに来た。

2. 洗濯しに帰った。= I’ve come home to do laundry. 洗濯する (sentaku suru) = to do laundry The pre-ます of する (suru) “to do” is し (shi) 帰った (kaetta) - past tense of 帰る

You can also add more information to your sentence, like adding the object of your pre-ますverb and the place you’re doing it.

3. コーヒーを飲みに喫茶店に行きたい。 コーヒー (koーhiー) - coffee 飲み (nomi) - pre-ますof 飲む (nomu) “to drink” 喫茶店 (kissaten) - teahouse 行きたい (ikitai) - たい(tai) form of 行く. This form indicates want. “want to go” = I want to go to the kissaten to drink coffee.

Now let’s go back to Shadis’ question to Armin.

Shadis: 何(を)しにここに来た?!?? NANI (wo) SHI NI KOKO NI KITA?!?? 何 (nani) 何をする (nani wo suru) - do what? (Shadis dropped the を(wo) object particle, Japanese sometimes do that in casual conversations.) ここ (koko) - here = What did you come here for (to do)?

You can answer the question using the same sentence form. However, in the anime, the soldiers used a different format: the ため (tame) format, which puts more emphasize on their “purpose/reason” for enlisting. We’ll look into it in a later post. :> 

For now, here are sample sentences that can be answers to Shadis’ question.

人類の勝利の役に立ちに来た。

調査兵団に入りに来た。

巨人を殺しに来た。

シャーディス教官に会いに来た。

I’ll give the vocabulary. You know the gist. 

人類 (jinrui) - humankind

勝利 (shouri) - victory

人類の勝利 (jinrui no shouri)- humanity’s victory

役に立つ (yaku ni tatsu) - to be useful

調査兵団 (chousa heidan) - Survey Corps

入る (hairu) - to enter

巨人 (kyojin) - titan

殺す (korosu) - to kill

シャーディス教官 (shaーdisu kyoukan)- Instructor Shadis

会う (au) - to meet | [person]に会う = “to meet [person]”

日本語 (nihongo) - Japanese language

習う (narau) - to learn

みんな (minna) - everyone, you all

一緒(に) ((issho (ni)) - together ~と(to)一緒に "together with~”

蛍 (hotaru) - firefly

蛍ジン (hotaru jin) - 😝

-ちゃん (chan) - a suffix attached to the name by the speaker. Usually used between girl friends and to refer to a female friend or to a child.

の (no) -  の at the end of a question sentence serves as something like a question mark.

みんなは何をしにこのページに来たの？ 蛍ジンちゃんと一緒に日本語を習いに来たね。^_^