Celine

Celine is Lala 's gift for Rito's 16th birthday. She is sort of a child-like humanoid/plant hybrid, but originally was a multi-story, carnivorous, sentient sunflower kept in the Yuuki's residence backyard. Although seemingly monstrous, Rito cares for Celine deeply, referring to her as his family. The plant behaves akin to a human; perspiring when the climate is humid, wearing an oversized scarf during a chilly day and eating a bowl of ramen when hungry (though Celine still needs the basic nutrients of water and sunlight). When Celine seemed to have contracted a deadly disease, Rito was fully dedicated to find the Luckberry to save her from the Kare Kare disease. With his friends, they journey to the S-level-danger class planet Misletoe to retrieve the antidote, only to return and find the plant all dried up. In reality, it was germinating and from its single seed, burst out Celine; taking the appearance of an infant girl, with a flower on her head. This event even shocked Momo, who is very knowledgeable with the galaxy's flora, stating Celine's biological makeup is still a complete mystery to her.

The infant Celine develops a low tolerance for cola (she gets drunk) and can spray pollen from the flower on her head that temporarily causes anyone who inhales it to fall in love with Rito – a side-effect that originates from Celine's own affection for him from taking care of her every day. The person who is sprayed with the pollen also immediantly sprouts a flower with lips on top of their head. When the effects wear off the flower also falls off their head and the person has no memory of what happened. A running gag as a child is Celine will playfully tackle any girl and attempt to suck milk from their breasts, or jump onto someone out of nowhere, most of the time causing the incident for the chapter's story. Comically mistaken for being Rito's daughter, Celine makes guest star appearances in the OVA adaptation (as a plant near the end of OVA 4 and as an infant in OVA 6 part 3) and becomes a regular character with her infant form in the new anime series.

Abilities
Being originally a plant, she has a connection with other plants like Rito and Momo do, so it's possible that, like Momo, she can also communicate with plants. Even though she talks in a somewhat baby-like language, Momo is still able to understand her.

Because of her parental love for Rito, whenever she gets drunk (off cola), she playfully walks around spraying pollen out of the flower on her head, causing anyone who breathes in this pollen to grow a tiny flower on their head and temperarily fall in love with Rito. The effects wear off after a while and flower falls off of their head.

Rito Yuuki
Ever since Lala gave her as a gift to Rito on his 16th birthday, he has been taking good care of her as if she was part of his family, this great deal of care for Celine was shown when was willing to go up againts impossible and dangerous odds to retrive a cure for her. She see's Rito as her parent because of how he took care of her and because of her child-like apperance and her closeness with him she is often mistaken as his daughter, like the time when Rito's mother though he was her dad she immediately who was the mother. She is one of the few characters with unique traits that causes trouble for him.

Mikan Yuuki
Mikan and Celine get along realy well and they are seen playing together on some accasions, sometimes Celine would copy Mikan's motherly personality. Mikan was the one who named her.

Yui Kotegawa
Celine has shown a liking to Yui, she would also have a playful moment with Celine. She is often mistaken for being Celine's mother and in a way as Rito's wife to which she greatly denise, beause of this Yui would sometimes have day dreams about the three of them as a family.

Trivia

 * She and Mikan are customers at the Stray Cat in the manga series Mayoi Neko Overrun! in Chapter 1, page 37.