aishite,
You can get the exersaucer from many places, taka, robinsons, isetan, kiddy palace, kidsmall etc. I know of the brand, 'Safety 1st', I have a pass down from my relative. I think it can last till the baby learns to walk i guess. Once the baby knows to walk, don't think he wants to go into the exersaucer. Frankly, it depends on individual, my boy don't really likes it, he prefers the walker which he can zoom freely around.