DouKaku?

shopt -s extglob
declare -i age

function readRecord() {
    local n=$1
    local s d

    read -n 12 s
    family_name[$n]=${s%%+( )}

    read -n 12 s
    first_name[$n]=${s%%+( )}

    read -n 1 sex[$n]
    read -n 3 age[$n]
    read -n 4 year[$n]
    read -n 2 mon[$n]

    for ((d = 0; d < 31; d++));do
        eval read -n 2 date_$d[$n]

        read -n 500 s
        eval "breakfast_$d[$n]='${s%%+( )}'"

        read -n 500 s
        eval "lunch$d[$n]='${s%%+( )}'"

        read -n 500 s
        eval "dinner_$d[$n]='${s%%+( )}'"
    done
}

for ((i = 0; i < 500; i++));do
    readRecord $i
done < data.txt