Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_18254488_2 (position VARCHAR, player VARCHAR)

### Question ###
When koki mizuno is the player how man positions are there?

### Accurate SQL ###

SELECT COUNT(position) FROM table_18254488_2 WHERE player = "Koki Mizuno"