Wow, can't believe how everyone didn't see Ikeuchi getting a comeback, he was going to become an end boss eventually.
He had several moments where he grew huge grudge to both Claire and Shuichi.
Claire and Shuichi created the whole problem by sheer ignorance, he was left out, they didn't bother much to search for him when he went awol after Claire chosen him to be a sacrifice for Madoka and carrying out her plan without him, it was bound to happen and now they will face the consequences of own actions.