Sao Paulo has the largest Japanese population outside Japan, so a culture tour usually means a half- or full-day guided experience that takes you through Liberdade neighborhood, a Japanese temple, a museum or two, and ends with a meal. Expect a mix of history lessons, quick stops at shops selling snacks and souvenirs, and a somewhat rushed feeling if your group is large. The actual Japanese cultural part is authentic but adapted to Brazilian tastes; it's interesting if you're into diaspora stories, less so if you want deep traditional immersion like you'd get in Kyoto.
Best time is March to May or September to November when it's milder and there's less rain. Avoid Carnival week and the peak summer heat (Dec-Feb). Expect to pay around $80-150 per person for a standard half-day tour including transport and lunch; full-day versions with more sites run $180-250. Private tours cost noticeably more.
Pick the tours that include a proper kaiseki-style or at least decent sushi lunch and a temple visit; skip the ones that overload the itinerary with too many souvenir shops or feel like they're mostly shuttling you between places for photos. Wear comfortable shoes; you'll do more walking than the description suggests.