Back in the prefecturals (the last official match Shishido played in singles) he got destroyed by Pref! Tachibana (who got destroyed by Pref! Kirihara) since then, he has improved his speed and sight. He has his rising shot (that seems like an actually good move, it won 2 straight points against the Golden Pair in the Nationals), and a great speed and stamina (he's a huge retriever).
Kikumaru, on the other hand, greatly improved his stamina and speed (he can play his "1 man doubles" for... an entire set? that's a lot), he even got smarter (enough to change his playstyle depending on his rival) and can almost perfectly emulate Oishi's Moon Volley. He obviously also has his acrobatic play (he doesn't really depend on it anymore though).
Overall, Kikumaru is faster, more versatile, and has some great techs. If it's a quick match, he stomps Shishido. Otw, I'd say it's prolly 6-3. In any case, Eiji wins.