In general, the graduation of the original Kami 7 can be considered as this. Since they are arguably the most revered members coupled with them are there since the group formations. Mayu Watanabe graduation hits especcially hard since she is the last to graduate AND just three years later she is retired from entertainment industry altogether.
Atsuko Maeda's solo reprise of Sakura no Hanabiratachi
In their early days, the girls had to give flyers to everyone outside the theatre as a promotion. Minami Takahashi once recalls that one person dumps the flyers into thrash bin when Takamina are nearby.
The MV of 'Mata Aeru hi Made', Minami Minegishi's graduation song depicts her lights 21 candles. Representing the 21 members of the 1st generation. The lyrics as well as Miichan struggles to hold her tears near the end of the video only makes the song more gut wrenching
With Minami Minegishi graduation in 2020, only Yuki Kashiwagi left from the original team note 1st, 2nd, and 3rd generations, with her on the way to fulfill her promise to remaining an idol until she turns 30. Meaning 2021 could be the end of the original team era since their debut in 2006
Watching the PV for 'Sakura no Ki ni Narou' along with the lyrics.
Seeing your oshimen announce their graduation or watch their graduation ceremony.
Most of the girls' reactions when the team shuffle was announced at the 2012 Tokyo Dome concert.
"Hakimono to Kasa no Monogatari" from Green Flash, an almost funereal ballad about two widowed shopkeepers in the countryside who ended up being each other's friends in their twilight years.
The song "Rider". It's a song dedicated to a loyal fan who passed away.
"Keibetsu Shiteita Aijō". Both the song itself and the video. Considering that it deals with the topics of bullying and suicide, it's hardly surprising.
In similar veins, the video and the lyrics of "Seifuku ga Jama o Suru" is both tear jerking and disturbing. The lyrics itself deals with Compensated Dating coupled with the TV ads adding "Otousan, gomennasai" note "Sorry, Dad" line and the video dark atmosphere makes the song highly controversial.
For those who are supporting the group since their formative years, watching the MV of "Sustainable" certainly count. The MV itself despite being set on a summer day has Revisiting the Roots concept in which the major points of the group journey echoed in the MV through showing the places that involved in past singles or similar scenes. Jurina's expression in the closing scene when she opens the time capsule gives a strong impression of about the current condition of the group after many prominent members are graduated and the aftermath of Maho Yamaguchi's scandal that affected the group massively.