We call that to "Nice Boat" somebody. The final episode was banned and/or delayed on some Japanese TV stations due to an unrelated incident of a girl killing her father with an axe around the same time. Consequently, stock footage like a boat traveling through a river was used, with an internet user captioning a still frame "Nice Boat," and the rest is self-explanatory.
As was
spoiled (Who can spoil shit?) said pages back, the girl who murders him, Sekai, is killed by Kotonoha, who still loves Makoto to the point that she beheaded his corpse's head for her own necrophiliac pleasures. Oh, and in the end, she's on a boat with it. Remember, this is the character MadThad0890 called his waifu.
Lastly, Sakai pretended to be pregnant to try to keep Makoto with him, who along to Kotonoha, told her to get an abortion. When killing her, she actually CHECKS for this and affirms it to be bullshit. It appears Damien is trying to emulate his life like School Days in the most autistic ways possible, from allegedly convincing Yaya to get an abortion, to threats about meeting up along a canal. I wonder if he'll see any nice boats? Or, he's an attention whore using Yaya's profile to reinforce his sexism.