Shingo Sawatari/Relationship

Lackies
Similar to Chazz from GX, Shingo is admired by his friends. However, it is shown that they secretly get annoyed by his selfish attitude but don't seem to really care. When Shingo lost consciousness after his loss to Yūto, his friends took him to the hospital. They also admired his amazing second duel with Yūya due to his multiple Pendulum Summons

Reiji Akaba
Shingo is shown to greatly respect and admire Reiji's dueling abilities as shown when he bragged about how he was well known for his multiple summoning methods to Dennis. Reiji in return, is shown to have some faith in Shingo's abilities as shown by how he entrusted Shingo with the task of taking Yūya's Pendulum summons, had him test a Yosenju Pendulum deck, and had him become a Lancer to aide the others during the invasion by the Obelisk force. Reiji also taught Shingo how to Pendulum summon.

Yuya Sakaki
At first, due to his task of stealing Yūya's pendulum monsters as well as kidnap his friend to force him to duel in order to test them, Yūya hated Shingo. Shingo's defeat at Yūya's hands and losing the Pendulum cards caused Shingo to form a bitter rivalry with him. However, things changed during their second duel in which they both seemed to have gained great respect for each other. After generously offering to duel Yūya anytime the latter wanted, they appeared to have buried the past and became friends. Although their behaviors still seem to annoy each other, they still appear to be concern for each other in important scenarios such as when Yūya lost Yuzu and Shingo was defeated and captured by Security.