Safu (沙布) is now a 16 yr old girl living in No. 6 and attends the same school as Shion . Shion is her love interest.
On Shion's 12th birthday, she invited Shion over and baked a cake for him also giving him a sweater as a present.
Four years on, she was chosen to go study aboard to the city No. 5 for two years. She seems to be very fond of Shion's decisions, especially when she asked him what is it that wants to achieve and what are his hopes for the future. She is also very straight foward as she asked for Shion's sperm.
She returned to No. 6 in episode 6 because something happened to her grandmother and episode 6 also reveals she might have a connection with Nezumi because both fainted after hearing a song.
In episode 6, her grandmother died and after knowing that Shion has committed a murder, she ran to Shion's mum and she then confessed her love for Shion to her. Planning to go and save Shion, she was kidnapped by the Public Security Bureau.
Episode 8, she will used as a sample, it is unknown what kind of sample.