You can spend an afternoon studying the exhibits at Toyohashi City Museum of Art and History during your travels in Toyohashi. While you're in the area, wander around the parks.
Explore the great outdoors at Toyohashi Zoo and Botanical Park, a lovely green space in Toyohashi. While you're in the area, wander around the gardens.
Catch an event at Aqua Arena Toyohashi during your trip to Toyohashi. While you're in the area, wander around the parks.