Uncertainty - darou, deshou, kashira

Deshou

The word deshou, which comes from desu, when used in a question followed by ka, is the equivalent of "I wonder...". When used with a rising intonation, it is asking for agreement so it is similar to ne but softer and less direct. Used with a falling intonation, the sentence is often translated using "probably", "must be" or "almost certainly". Also deshou may be used in place of desu for extra politeness.

これは何ですか。これは何でしょうか。
Kore wa nan desu ka. Kore wa nan deshou ka.
What's this? I wonder what this is?

あれはわたなべさんのうちでしょう。
Are wa Watanabe san no uchi deshou. [Rising intonation]
That's Mr. Watanabe's house, right?

北海道は今寒いでしょう。
Hokkaidou wa ima samui deshou. [Falling intonation]
It's probably cold in Hokkaido now.

すみませんが、田中さんでしょうか。
Sumimasen ga, Tanaka san deshou ka.
Excuse me, but would you be Mr. Tanaka?

Darou

The plain form of deshou is darou. It is in most situation considered informal and can be a bit ruder.

誰だろう。
dare darou?
Who is it? (thinking for yourself)

Kashira

Kashira is a feminine expression for showing uncertainty.

• tabeta kashira?
  Did I eat it, I wonder?