A2
ましょう and よう — let’s, shall we
How the Japanese volitional form works, the difference between ましょう and ましょうか, and how it expresses intention as well as invitation.
ます becomes ましょう.
行きましょう。
Ikimashō.
Let’s go.
ちょっと休みましょう。
Chotto yasumimashō.
Let’s take a short break.
ましょうか — shall I, shall we
Adding か turns a decision into a question, which is softer and often more polite.
窓を開けましょうか。
Mado o akemashō ka.
Shall I open the window?
何を食べましょうか。
Nani o tabemashō ka.
What shall we eat?
The same form covers shall I and shall we; who is meant comes from context.
The plain form
う or よう, by the same split as everywhere else: 飲む → 飲もう, 食べる → 食べよう, する → しよう, 来る → 来よう.
そろそろ帰ろう。
Sorosoro kaerō.
Let’s head home soon.
It also states an intention
Followed by と思う it stops being an invitation and becomes something you have decided for yourself.
日本語を勉強しようと思います。
Nihongo o benkyō shiyō to omoimasu.
I’m thinking of studying Japanese.
Not an invitation to someone senior
ましょう assumes the other person will agree, which is presumptuous upwards. An invitation is safer as a negative question — see か.
部長、飲みに行きましょう。
部長、飲みに行きませんか。
ましょう decides for both of you. ませんか leaves the decision with them, which is what makes it the polite form of an invitation.