V. Question word : Itsu

Itsu is used to ask time and means "when."

Examples
1. Itsu Nihon e kimashita ka.
"When did you come to Japan?"
2. Daigaku e wa itsu ikimasu ka.
"When do you go to the university?"

NOTES ON CONVERSATIONAL GRAMMAR
Response : "Soo desu ka."
Example
Satoo : Sono hon wa senmon no hon desu ka.
"Is that book one your speciality?"
Lwin : Iie, kore wa Nihongo no kyookasho desu.
"No, it's a Japanese textbook."
Satoo : Soo desu ka.
"I see."

In the above example, "Soo desu ka." is not a question. Satoo is conveying to Lwin a signal of his understanding of what Lwin said. It can also be said that Satoo is giving
a response that makes a conversation go smoothly.
When "Soo desu ka." pronounced with a falling intonation, it means "I see." When it is pronounced with a rising intonation, it shows a doubt or something
unbelievable.