A type of weak question mark. Tends to be in informal speech but unlike "kai" and "dai" can sometimes be used after "desu". Asks questions in an indirect way, so tends to be in female speech more than male speech. Nevertheless, men use it. Can be used for both yes/no questions and questions requiring more substantial answers. To a friend: "Achira ikebana no sensei ka shira." I wonder if that is the ikebana teacher over there... "Sono obi ha dou yatte somerareta ka shira." I wonder how that obi was dyed. To say "wondered" (past tense) use "ka shira to omotta."