Sora

Abandoned by his parents, Sora is a brilliant NEET hikikomori gamer along with his stepsister, Shiro. He does not take life very seriously and is pretty much a good-for-nothing gamer. One day, he and his sister are called into an alternate world.

Sora is tall and thin with spiky brown hair, and constantly wears a sly grin on his face. Despite being a NEET and a shut in, Sora is extremely outgoing and confident, and is not afraid to play games with people face-to-face, even when they are cheating. He is also extremely manipulative, which he refers to as using negotiating skills. This fits in with his play style. While Shiro is excellent at logic and computing, Sora can read people and predict what their next move is, using this knowledge to beat them.

However, if he is separated from Shiro by so much as a closed door, he becomes a spineless, cowardly wreck, and only returns to his former self if he is able to see her. He views his sister as his equal and partner, but is also protective of her, shown by actions such as putting his body between her and the ground when he thought they were going to hit hard when first arriving on Disboard.

Sora is extroverted and has no problems dealing with people. While not as intelligent as Shiro, he is shown to have a brilliant IQ. Rather than computing numbers like Shiro, Sora can rapidly compute what his opponents are going to do based on observing their behavior and motivations. He is also slightly perverted and desires a girlfriend for himself. His lust leads to a linguistic mistake that causes Stephanie to fall in love with him and causes him to receive a scolding from Shiro.

(Source: No Game No Life Wiki)