Although busy & enjoyable, in this particular position (fulfilment) there isn't really much opportunity to advance in the company within this role. Its more suitable for somebody with a lower level Japanese ability, or for someone who is looking for a job without too much responsibility. However if you do want to take on some extra tasks, you only need to ask & they will endeavor to find something extra for you. If you have a good Japanese ability or are looking for more of a career path, then I would encourage you to apply for a back office position (buyer, customer service, admin ect).