Guadalcanal isn't really a good example of Japanese use of submarines for supply. As to numbers, the Japanese built several hundred submarines particularly, their 2nd class types (Kaitokuchu) like the R0's and late war Sentakasho (fast small type) Ha's. They didn't build as many of the larger fleet type submarines (these displace about half again to double what German boats did) Sensuikan Kadai and Junsen types simply because these were expensive, long term builds compared to the second class boats (which compare with the German Type VII).
At Guadalcanal, the Japanese supply line was maintained by a combination of destroyer delivered supplies and gross wastage in merchant shipping. The later was usually simply run aground and emptied as best as the troops could manage. On the whole, the Japanese supply attempts at Guadalcanal were ill-conceived and poorly carried out.