It's common knowledge that spending a little time surrounded by greenery can increase your energy. If walking around town has tired you out, Sorosenen is a perfect place to relax and recharge your batteries.
You're spoiled for sightseeing choice when in Koganei. Sorosenen is a great place to kick off here, but there are many other worthy sights to appreciate. Ghibli Museum, Yomiuriland, and Ajinomoto Stadium are near the recreation and green space and will round out your day nicely.