The "Death" Of Shini Takashi

The first documented death of Shini Takashi took place in March 2012. Investigator Makamura and Gen were there to witness it. The ghoul Camo was involved,

Prelude
Antoine was investigating the recent death of Haru Moto, an infamous fashion designer in Tokyo. It was believed he was killed by the ghoul given the title of the Jorogumo. Gen had come with him since Antoine had asked for his assistance.

Course of Action
Antoine took Gen to investigate the old whereabouts of the Yamata no Orochi ghoul since it was believed the Jorogumo had a relationship of some sort with him. The two ended up finding Camo and Shini Takshi fighting in the apartment complex. When Camo noticed the Doves, he brutally attacked Shini, ripping her insides out and tearing off her head. Gen was traumatized for she looked him in the eyes and called out for help as she died. Camo fled the scene only to have Antoine follow in order to kill him too. Gen stayed behind for a few minutes to stare in horror at Shini's remains before following Antoine in pursuit.

After returning to CCG's headquarters in the first ward, Antoine disclosed Shini's identity to Gen, this is where his obsession with her stems from.