Relevant Sources:
– He would also say: Those who are born will die, and the dead will live. The living will be judged, to learn, to teach and to comprehend that He is G-d, He is the former, He is the creator, He is the comprehender, He is the judge, He is the witness, He is the plaintiff, and He will judge. Blessed is He, for before Him there is no wrong, no forgetting, no favoritism, and no taking of bribes; know, that everything is according to the reckoning. Let not your heart convince you that the grave is your escape; for against your will you are formed, against your will you are born, against your will you live, against your will you die, and against your will you are destined to give a judgement and accounting before the king, king of all kings, the Holy One, blessed be He. (Pirkei Avot 4:22)
– Sins committed against other people, including hurting someone's feelings. Yom Kippur does not atone for these sins until the perpetrator gains forgiveness from the victim himself. (Orach Chaim 606:1)