Question regarding Softbank Prepaid Plan

I've stayed in Japan for one year and used a Softbank Phone with prepaid service during this year. I last topped up my balance in June 2015 as then my year in Japan was over and I moved back to my home country. I of course kept the phone.

I am now planning a two-week holiday in August 2016 in Japan and hoped I could just use my Softbank phone again. However, I am now trying to figure out if my number would still be valid by then or if I would need a new SIM-card? The service guide of my phone says something of 'Number remains active for 360 days after account expiration' and 'Register a prepaid card before expiry to keep the number' but I do not understand when my account expires and it just confuses me.
I originally thought the number would be valid for 360 days after the last top so my sim card would be deactivated in July...

Can anyone help me to figure this out? Is my number still valid in August? When exactly is the expiration date of my card?

The system is that your credit is valid for 60 days after your last recharge, and you number remains valid for an additional 360 days after your credit expires. In practice this means that your number will be valid for 420 days after your last recharge. Here's an english guide that explains it. It's a few years old but I'm pretty sure that the system hasn't changed:

http://cdn.softbank.jp/en/mobile/set/data/service/prepaid/shared/servi...