Honkai Impact 3rd vs BlazBlue
Connection:
Both are female video game characters who are artificial human clones of young innocent girls (the real Kiana Kaslana and Saya respectively) with a dark history that belonged to another being (Sirin/Herrscher of the Void and Mu-12 respectively) and have been adopted by surrogate parental figures (Siegfried Kaslana and the Vermillions)
Both their worlds are filled with radioactive energy (Honkai energy and Seithr respectively) formed by a complex and cosmological space that connects every known world in their respective multiverses together, which supposedly also lacks concept and thus potentially grants them limitless power (the Imaginary Tree and Boundary, respectively)
Both are designed to kill the godlike forces that seek to destroy their world (Will of Honkai and Original Units respectively)
Both enroll in a military academy (St. Freya High and Control Organization respectively) where they meet close friends that they would end up fighting in a bitter struggle in the future (Raiden Mei for Kiana and Tsubaki Yayoi for Noel)
Both are manipulated by handsome villains (Otto Apocalypse and Hazama respectively) which awakened their suppressed evil persona, who wants to destroy the world. Said rampage is stopped by a sacrifice made from a protagonist in red (Himeko Murata for Kiana and Ragna the Bloodedge for Noel), and they regain control of themselves.
After confronting their other half, they gain full control of their powers and make up with their closest friends. They would go on to fight apocalyptic beings that exist on and have powers from a higher plane of existence (Otto Apocalypse and Black Beast)
By the end of their stories, they learn to accept that the person who saved them is truly dead and never coming back, breaking down into tears doing so
Both fight with a gunkata fighting style initially. When they transform, they can create weapons that they fight with piercing weapons (Herrscher of the Void used lances and Mu-12 used swords) and have spatial manipulation powers
Both are also a form of successor in a way (Kiana is the Herrscher of Flamescion, "scion" of which stands for successor and is a nod to how she took up Himeko's flames as her own, while Noel is viewed as the Successor of the Azure)
Both are also known for being terrible cooks (Kiana inheriting it from her Kaslana heritage and Noel's cooking being known as the "Death Dinner")
Both their series also had crossovers (Honkai Impact 3rd had a crossover event with Genshin Impact, which is also created by miHoYo. BlazBlue had a crossover game called Cross Tag Battle with RWBY, Persona 4 and Under Night In-Birth, with Arcana Heart, Senran Kagura and Akatsuki Blitzkampf being DLCs)
