User blog comment:B214/High School DxD Hero Discussion/@comment-89.164.205.227-20171021221749/@comment-29963364-20171021232826

1.) Yes. Issei can "sheath and unsheath" his scale mail wings anytime he chooses.

But, if we're staying true to the LN, Issei's scale mail got wings after he first activated Juggernaut Drive in vol.6 (during his first battle with Shalba Beelzebub), but the BorN anime gave him wings immediately when he unlocked Balance Breaker (which happens in LN vol.5, or BorN episode 3 ).

2.) In the BorN anime, from Episode 3 -12 (basically the entire season) was completely "anime-only." They practically ignored the Young Devils Gathering (a Rating Game tounament between the strongest of the young Devils) and focused on a terrible recreation of the Battle with Loki.

In my own opinion, if this new season (HERO) stays true to the original LN material, then fans can just ignore/skip BorN and enjoy the rest of the story.