Aside from his grandmother: who would Toshiro consider the most Maternal figure in his life?
Maternal? No one. — He has his Grandmother who raised him since he was an infant which is why she means everything to him. ———- But be that as it may, he does have men and women, older figures, he looks up to, who helped him in some way or fashion in maturing into who he currently is, like Ukitake, Kyoraku, Byakuya, Kaien, Kaname, Fake Aizen // Coughs //, Unohana, Hinamori, even Kensei and Soifon. E.T.C. —– And it’s fair to say that Rangiku, despite their unshy bickering, has become a canon older sister character he never wanted but would unhesitatingly protect with his life. - Then there are other muses like Peach, Judith, Levy, Gajeel, and Fang e.t.c who helps him in communicating with others and the like.