Display case

A display case, comprising:

• a case main body having a square plate shape, and including a first surface and a second surface on a side opposite to the first surface;
• paired first connection portions protruding from paired first sides of an outer edge portion of the case main body;
• paired second connection portions protruding from paired second sides of the outer edge portion, and protruding at positions closer to the case main body than the paired first connection portions;
• paired first side-wall portions each configured to be turnable between a first position where the first side-wall portion stands up from the case main body and a second position where the first side-wall portion falls down on the case main body, around the corresponding one of the paired first connection portions, and each including first engagement portions;
• paired second side-wall portions each configured to be turnable between a third position where the second side-wall portion stands up from the case main body and a fourth position where the second side-wall portion falls down on the case main body, around the corresponding one of the paired second connection portions, and each including second engagement portions;
• a plurality of placement portions provided at respective corners on the first surface of the case main body;
• a plurality of joint portions placed on the respective placement portions, each of the plurality of joint portions including third engagement portions engageable with and disengageable from the first engagement portions of the turning first side-wall portion, and fourth engagement portions engageable with and disengageable from the second engagement portions of the turning second side-wall portion, the plurality of joint portions being configured to turn with the first side-wall portions turning to the second position, to expose the placement portions;
• at least one paired first convex portions provided at paired corner portions at diagonal positions on the second surface;
• a plurality of first concave portions provided on respective top parts of the plurality of joint portions and each having a shape complementary to the shape of each of the first convex portions;
• and
• a plurality of second concave portions provided on the plurality of placement portions and each having a shape complementary to the shape of each of the first convex portions.