Processing
Junen (rolling)
Rolling the steamed leaf to even out its moisture and break the cells just enough that the tea gives up its flavor quickly in hot water. The needle shape of sencha comes from the final shaping stage that follows.
In more detail
It is not one action but a sequence — rough rolling, rolling proper, secondary rolling and final shaping. The first drives off moisture while working the leaf, the second evens the moisture out, the third dries it again, and the last draws it into fine needles. That needle shape comes entirely from the final stage; tamaryokucha skips it and stays curled.