japanese book on helmets

new to this forum....just wondering if there's a great book on japanese helmets of ww2 only. i have a helmet that is unlike any i've seen before. the front of the helmet is longer than usual (seen those before), it's been repainted,got the anchor on the front,on the front brim inside it's got three enterlooping circles stamp in it, inside the rear brim it has the letter "n" with a circle around it ,and the usual character mark on it. but the thing that's puzzling to me is the liner, it's a leather of somekind with 3 pads . but the neck strap isn't connected like i've seen before. instead of the usual one on each side plus one in the back, it's connected in a Y fashion on each side. connected to two swivels on each side, then you just tie it together under your chin..the strap also has japanese writing on one of them. i'm thinking the helmet is real but i don't about the rest. p.s. bought it at a local estate sale..thanks for any help

 

just wanted to add.. i know it's hard to say anything without photos. i'll get some posted once my son comes home.. just thought by the description someone might know.. or a good website ... or book thanks again