Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_99 (date VARCHAR, opponent_in_the_final VARCHAR, surface VARCHAR)
### Question:
On what date did the opponent in the Toshiaki Sakai final play on a grass surface?
### Answer:
SELECT date FROM table_name_99 WHERE opponent_in_the_final = "toshiaki sakai" AND surface = "grass"