"I am Sein, the light and the eyes of the Spirit Tree. I was lost in this glen when she loosened her grip. I can guide you on your journey, if you allow me to come."
Sein is a supporting character in Ori and the Blind Forest. A creature containing the power of the Spirit Tree and its will, Sein acts as both a guide and a weapon to Ori during their journey to restore Nibel.
Sein is a floating, globular being made of blue light who always hovers around Ori's immediate vicinity. It communicates by chanting in an unknown language, often rhyming (or loosely rhyming) as it does so.
With detailed knowledge of how the forest became blind, Sein acts as a guide for Ori to learn about the new world they find themselves in. It is thoroughly dedicated to its mission regardless of what happens, though also shows a great care for Ori as a remnant of the Spirit Tree itself.
- Warning! Spoilers ahead.
During the Light Ceremony that was designed to call Ori back to the Spirit Tree after they were separated during the Great Storm, Kuro attacked the Tree and stole Sein from the higher branches. Crushing the being in her talons and dumping it into the forest, Sein's absence from the Spirit Tree triggered the decay of Nibel and its forest.
After Naru's death and escaping from their own blighted home, Ori encounters Sein in the Sunken Glades and reawakens them thanks to being a Spirit Guardian. Together, the pair of them travel back to the Spirit Tree where Sein explains the situation that Ori is the only one capable of rekindling the three Elements of Light.
Throughout the journey, Sein makes deductions about the things that Ori and it encounter and often makes suggestions about how best to proceed. It also shows a great level of concern for Ori during perilous moments, showing the parental care of the Spirit Tree resides within it.
At the conclusion of the story, Sein shows clear alarm for Ori when the Spirit Guardian is knocked unconscious by Kuro's talons. Thanks to Naru's motherly instincts for Ori, Kuro realises the gravitas of what she has done and atones by taking Sein back to the Spirit Tree. The light merges with its former home and restores the balance of Nibel, allowing new Spirit Guardians to once again be born and the forest to be clear once again.
Sein acts as Ori's main offensive capability against the enemies that they encounter. It is able to use Spirit Flame, an ability which sends out streaking rays of light to damage foes. Charging up this power with a Charge Flame amplifies the damage output and is able to blast through the toughest of obstacles, at just the cost of one(or half of an) Energy Cell. As with most of Ori's powers, Sein's abilities can be upgraded and enhanced throughout the journey the more experience Ori gains.
Apart from this, Sein teaches Ori about the world around them and the state of the forest in the wake of the blinding. With detailed knowledge of Ori's kind and various sights they encounter in Nibel, Sein's primary function and ability is to be a source of information throughout the journey.
- Sein is labelled as Ori in the Debug Menu, and vice versa. This implies that Ori and Sein's name were once swapped.
- Sein was named after the German verb for "to be" or "to exist".
- Sein's voice is portrayed by Aeralie Brighton. She can also be heard singing on the soundtrack of the game.
- To control Sein, all you need to do is tap/hold the X button. Which coincidentally is blue, just like Sein.