The character I most relate to is Rin Shima from Yuru Camp.
Like me she's an introvert who is happiest doing her own thing in her own time on her own. But, also like me, she's not anti-social and she will join in with other people and go out with them if she's asked and given the opportunity to decline and is not forced to join in. She is softly spoken and is willing to share her knowledge and interests with people if they're interested, but she won't force herself on people although she does care for her friends, often quietly and sometimes secretly.