Light’s Plan
After Rem had left, Light revealed to Ryuk the details of his plan: He would persuade L to imprison him and keep him under 24-hour surveillance. He would then renounce ownership of the Death Note and, like Misa, lose all memory of it, Ryuk and Rem.
L and Near
L is dead and he will not return. N (Near) becomes L’s successor and attempts to catch Kira.
Memory Regain
After they defeated Higuchi, Light touches the rulebook and temporarily regains his memories so he kills Higuchi and assumes ownership of it, thus permanently regain his memories.
Misa’s Memory
Misa regains her memories after cyber-terrorist Yuki Shien gives her a Death Note.
Gelus and Misa
Misa Amane Gelus, a Shinigami, fell in love with Misa Amane and used his Death Note to kill the man who was destined to kill her.
Loss of Memories
Because the actions of Misa Amane nearly implicates Light, he becomes compelled to temporarily relinquish ownership of his notebook and subsequently loses his memories of using the Death Note.
Soichiro’s Discovery
Soichiro definitively discovers that Light is Kira when he comes across Light shortly after Light retrieves the Death Note that was taken by Mello and Shoko Himura.