In the not-so-distant future, mankind is at war with itself. The lives of Chise and Shuu are torn apart when Chise is chosen to become the ultimate weapon to fight for Japan against their enemies. Death, sadness, and the hardships of love accompany Sai Kano in its grim look at war and its consequences.
On a distant planet, a war wages between humanity and the extraterrestrial Citizens of the Stars. Humans, in a desperate attempt to drive off their attackers, force enslaved beings known as Majins to fight for their cause. Strong-willed Yuuri is a member of the Superior Soldier Team - a group that is on the front lines of the war. She has been begrudgingly charged with the care of a Majin known as Number Seven - but as the fighting continues, Yuuri and Number Seven grow very close. Humanity is on the verge of extinction at the hands of the Citizens of the Stars; can Yuuri and Number Seven turn the tide of the war so they can be together forever?
Saikano and Hanoka are remarkably similar; each involves a young girl who is being exploited due to her nature as a living weapon. Hanoka is considerably less graphically appealing and overall flat out sucks, while Sai Kano is gorgeous, but also sucks. Regardless, if you liked one, you might enjoy the other.
Constable Fuse is part of an elite Special Forces unit known as the Capital Police whose mission is to maintain peace during a time of civil unrest. Fuse becomes entangled within a web of intrigue and politics between the Capital Police, the government intelligence bureau, and a secret society known as Jin-Roh – the Wolf Brigade.
Murao Mima has created a robot daughter named Key, but after raising her for a very short time, Mima dies, leaving behind cryptic messages telling Key how she can become human. Key must struggle alone to learn the harsh lessons of life and search for the 'key' to her own dream: the power of 30,000 friends to make her a real human girl.
With a past shrouded in mystery and a blank memory, Shiki Tohno seems to be just another "average high school student". That is, until he nearly kills a female vampire with his secret deadly ability to "see the lines". His journey to unlock the secrets of the Tohno family and unbury his own lost memories has only just begun, and now he must also help the woman, Arcueid Brunestud, find a lethal phantom named Roa, and kill it using his ability.
In the future, a devastating event known as Second Impact has destroyed Tokyo as we know it, giving rise to Tokyo III - a city under siege by mysterious lifeforms known only as Angels. Mankind's only line of defense are the Evangelions, a set man-made machines piloted by a trio of fourteen year-old teenagers, Rei, Shinji, and Asuka. The fate of Japan and the entire world now lie with these three children, though they might not have the power to save the most important thing of all: each other.
Both shows focus on young people and war and both deal with super powered weapons. However, the real connection to me was that Evangelion and Saikano can just crush you emotionally at times. Saikano has more romance, but if you like bad things happnening to characters you love, you'll enjoy both of these shows.
They also have a strangely similar ending despite not really sharing any story elements or really any type of plot connections at all.