Is $1000 enough for 7 days in Japan?

my husband will be chaperoning his little brother on his senior trip to Japan next March and he’s planned on bringing $1,000 (USD) to spend on souvenirs/food. All travel and accommodations are paid for so the $1K will be strictly for leisure spending and eating. he is wondering if this will be enough or if he should plan to bring more.

side note in case it’s relevant — he would like to do most of his shopping in akihabara as he’s a big video game/anime collector (DBZ).