Japan has custom to give gifts periodically to people such as teachers, relatives, bosses to express our gratitude for a long time. This custom is called “Ochugen”, and we regard this as seasonal greeting. The time to sending is different from the area, east of Japan is the beginning of July to 15th, and west of Japan is the beginning of August to 15th. The market price is around 3000~5000 yen, it depends on the relationship though. This custom is done in China, Taiwan and in Japan. This is sometimes troublesome, but I feel this is good opportunity to communicate with someone who is important but has not seen from.
You can see the trends from AEON website if you are worried what to send.