If you happen to have Friday off and are in the mood for sightseeing, would you like to visit Osaka Castle? Built in 1583 and rebuilt several times, Osaka's most prominent landmark features a history museum (with air conditioning :) ), while the Nishinomaru Garden offers plenty of photo spots. Skip-the-queue tickets are on sale on booking.com for 5,80 euro (that's the cheapest way I could find, to get in)