Beauty Mark: A quite noticeable one under his right eye.
Boring Invincible Hero: Averted in GP 8 as an Aesop. While helping Speedor recover from a bad rust, Sosuke kept believing that a miracle will happen, since they're the heroes; nothing happened. In the end, he decided to make miracles happen, rather than waiting for them.
During Shinkenger vs. Go-Onger, he's the red oni to Takeru's blue oni.
Serious Business: Though not to the extent of some other Rangers, since he does it mainly as a parody of 60s' Japanese daytime dramas.
Ship Tease: An early episode hinted that he might have romantic interest in Saki when he became worried about her spending time with a man outside the group (who, it turns out, she was asking for advice on how to defeat the Monster of the Week). He eventually gets heavy Belligerent Sexual Tension with Miu.
Beware the Nice Ones: Ren may be sweet but is not to be trifled with, as seen during GP 25 when he defends a Gaiark that he had believed for years was a sacred family statue, and in GP 35-36 following Sosuke's Disney Death
Ship Tease: It's occasionally hinted that Hanto has a crush on Kegareshia (in GP 14 he falls for her while she is disguised as "Rena", and in other episodes he seems to find her attractive even in her usual form).
Wholesome Crossdresser: In at least two episodes. Later, in GP 47 Gunpei wants Hanto to dress as a girl and pose for fake wedding photos to deceive Gunpei's mother, despite the presence of two actual women on the team.
Jumped at the Call: Desperate to become a Go-onger to the point of stealing the Engine Casts. It's only when he agrees to hand them back that Bomper decides Gunpei has a strong sense of justice, and allows him and Hanto to become Go-on Black and Green.
Ki Attacks: Ganga Ganga Dan, during the events of Go-onger vs. Gekiranger.
Real Men Hate Sugar: Subverted; after having a taste of a cake that Saki made (after Sosuke declared it to be delicious), he eagerly took a piece, saying, "I don't like sweets, but I'll have this."
In the finale, he tells Saki that he looks forward to the day when she opens her own cake shop. YMMV whether he has developed an appreciation for Saki's cakes and sweets, or if he is merely being a supportive friend.
All Girls Want Bad Boys: While Sosuke is brainwashed in the Straw Banki episode, he begins acting like a gangster/Yakuza and offers Miu a stolen ring, which makes her happy. Later, after he has returned to normal, she admits that she preferred him brainwashed.
Aloof Ally: At first, but she warms up to the Go-ongers much faster than Hiroto does.
The partners of the Go-Ongers, hailing from the Engine World. In order to survive on Earth they need to separate into Engine Casts, miniature versions of their true Engine forms, and Engine Souls, which are cartridge-shaped objects that store the soul of an Engine. When the Engine Casts are reunited with the Engine Souls, the Engines are brought back to full size for ten minutes, after which they risk rusting.
Even Evil Has Standards: Of particular note during GP 31, where he (along with his Gaiark colleagues) attempts to stop the MOTW. He gets special mention for explaining that they only want to dirty the world, not destroy it.