Have you received another yellow envelop from the city yet?
That must be the Child Allowance present condition form.
The form seems to be the same as last year's, so please refer this post to fill in.
Please remember that the deadline is June 30th (FRI), 2017!!!
If you bring it to your local ward office, they may have a letter box to collect the present condition forms (so that you don't have to pick the ticket to be called to the counter). In that case, be sure to write your name (basically the recipient's name, so it may be your partner's name) on the envelop and seal it with glue.
*If you are new to the city, you have to sign up at the ward office to receive the allowance.