We Agreed to Summon a Familiar, but Why Is the Style of Painting Two-Dimensional?

Traveling through a world where everyone has the potential to become a summoner, as a genius, Liu Bai felt that his start was not bad. But as a time traveler, Liu Bai's soul is a dark one. He can neither establish contact with the summoning realm of this world, the Sea of ​​Stars, nor can he form a bond with a familiar and sign a contract. Seeing that Tianhu's good start was actually played like this by himself, Liu Bai was already thinking about reincarnation in the next world. But at this moment, a girl with silver hair and red eyes suddenly appeared in front of Liu Bai. "Illya! Magical girl Illya! I came in response to your call. Master, do you want me to destroy the enemies in front of you?" "Magical girl... Illya?!" Liu Bai shouted to the world, but only the two-dimensional characters in his memories responded to his call. Could it be that... The ones he can summon are actually wives from the second dimension? What about Icarus, Yatogami Tohka, Tohsaka Rin, Rem, Madoka, Frilian... Even the characters in the game, Silk, Nasida, Longhua Concubine, Lily Garden Shengya, Ye Shunguang, Robin, Abigail... Can these all become my own familiars? What! It really works!