Based on the wording, this likely refers to:
: This specific volume is often categorised by its "Part 2" status, continuing themes established in her earlier series entry, often involving sophisticated or professional roles. Era Aesthetic sq evolution vol 5 mei sawai extra quality
line which stands for "Extra Quantum" and is the successor to the original SQ line. Context of "Extra Quality" : This phrase is sometimes used to describe the line's focus on high-detail textures and molding. Based on the wording, this likely refers to: