Yūki Saibai

Yūki Saibai is the father of Yūki Rito and Yūki Mikan, and the husband of Yūki Ringo. He works as a mangaka and is very different compared to Rito in terms of both looks and personality. He lives in his own apartment where he does his work as a mangaka, due to living really close he appears slightly more often in the series than his wife does. Saibai is known to possess great skills as a manga artist, one of his most notable skill is that he can draw at an amazing speed.

Appearance
Saibai has gold/brown eyes and slightly long and messy black hair, he seems to have big eyebrows. He is always seen wearing a dark blue shirt and a red headband that says "big haul".

Personality
Saibai can be utterly serious and determined in doing his manga drawings especially before deadlines are met, but seems to have a bit of a goofy side, such as making a joke about Rito and Lala "sleeping" together every night and punching Rito when he got drunk and mistook his son for a burglar. Like Mikan, he is very casual, even amused, with his son's relationship with an alien girl, something Rito finds perplexing about his family.

He feels that whenever he puts on his headband, his mood turns intense and his work marches right along, saying it's a case of form defining substance.

Plot
He first appeared in Chapter 11 when Rito went to his apartment to help with his manga before the due date, at the time he also brought Lala along which Saibai was aware that she was an alien from Mikan. Lala helps Saibai and his co-workers finish their work by using an unmaned invention that helps them draw faster, however his co-workers quit due to exhaustion, who Lala later replaced with Zastin, Maul and Smutts and are currently working under Saibai.

In the anime, he writes a (not-so-encouraging) letter to Rito at the end of the first season.

With the help of Lala, Saibai returns for the Christmas party, stating how much Zastin and his workers have grown since starting out.

Yūki Rito
Rito is Saibai's only son, whom he would occasionally ask to buy manga supplies for him or assist in drawing his mangas. If he were to say no to him, then his dad would not give him his monthly allowance, showing he has a stern parental approach to him. Even though he rarely sees him, it is obvious he still cares for his son, just as any father would.

Yūki Mikan
Mikan is Saibai's only daughter, whom he also would constantly ask along with Rito to bring in manga supplies to him with a bonus of helping clean up his apartment and cook food for him and his co-workers, which he really enjoys, saying it fuels up his stamina. Although Mikan finds it quite irritating especialy when he buys Momo's innocent act.

Yūki Ringo
His wife, whom he hardly ever sees due to her job as a fashion designer traveling around the world. But they do seem to still love and care for each other.

Lala Satalin Deviluke
Saibai seems to enjoy Lala's company and likes teasing Rito over his relationship with her, like how she sneaks into his bed naked. Lala would usualy call him "Rito Papa".

Momo Belia Deviluke
Momo would always try to make good impression around him, which seems to work, as he once mentioned that she would make a great wife. He is completely unaware of her lecherous side and is under the impression that she really is a kind and sweet young lady. Momo would occasionally call him "Father" (as in for Father-in-Law).

Zastin
Zastin, along with Maul and Smutts, currently work for Saibai as manga artists (with Zastin as chief assistant) ever since his previous assistants quit due to exhaustion when they used one of Lala's inventions to help them draw fast. Zastin, Maul and Smutts seem to enjoy their jobs as manga artists more than their jobs as bodyguards.

Etymology

 * Yūki means "tie, bind" (結) (yū) and "castle" (城) (ki).
 * Saibai means "talent" (才) (sai) and "cultivation" (培) (bai).